Old-age security system is an important part of social security system andsocalist market economy. In accordance with the requirement of the Decisionof the Third Plenary Session of the Forteenth Central Committee of CommunistParty of China, in our country, the ideal mode of old-age security system is,on the basis of the unity of rights and duties, to build an old-age securitymode with multi-channel funds resource, multi-level security methods andsocialized management and service.This thesis consists of four parts: Part one expounds Marxist main writer’stheory on old-age security system, part two analyzes the situation and problemexisting in the old-age security system in China, part three is on thedevelopment of old-age security in several countries whose mode are verytypical and whose experience deserve to be learnt, part four puts forward theideal mode of the old-age security system in our counny.In our country, the traditional elderly supported is mainly the one by thefamily Family is the primary unit of producing and consuming, elderly supportedalso takes the family as its unit. After the founding of PRC, the old-age securityin our country has made quite rapid progress. Under the system of plannedeconomic, based on the working unit, a mode of pay-as-you-go system wasbuilt. But with the gradual establishment of market economic system, more andmore problems by this mode have been exposed: first, this mode, in which thestate and enterprise were overburdened, while the burden of individual’s wastoo ligh, couldn’t effectively arouse the enthusiasm of the individual; secondly,this sort of old-age security mode, with low socialized degree, narrow rangeand poor mutual-aid, couldn’t scatter the risk of old-age support; thirdly, thismode couldn’t undergo the lashing of aging; what’s the most important of all,this mode not only fell far behind with the requirement of economic reformand social development but also has become an obstacle to the state-ownedenterprises’ further reform, and to the reconstruction of national economy andthe development of caPtal market. So in the econondc system reform, it is themost significant to construct a new old-age security mode adaPted to thesocialist markt economy.According to differnt distinction standards, there are different wayS ofclassifytng the old-age security mode, but no matter what method will beadoPted, the raising and payInent of the old-age pension are the keynote systemarrangement, so the mode of old-age pension’s raising and payInen can beconsidered as the mode of oldage security. In accodrice with thisclassilication, in every counny of the worid, there are three main modls asfOllows: pay-as-you-go system, funded system and pwhy accumulated system.After Md War TWo, influenced by the RePort of Wlliam BeVeridge, themain caPitalist countries, in general, adopted the pay-as-you-go system. Butafterward, the finance was overburdened because of the slow sPeed ofeconondc develoPment and the increase of aging, so there aPPeared thetransihon frOm pay-as-you-go system to funded system and partly accumulatedsystem. Owing to the mutual-learning and ndting, the boundaries of thesemodes are not very clear now. Generally spealdng, the fomr Soviet Union andChin4 before its reform and oPening, also adopted the pay-as-you-go system,Singapore and Chile funded mode. (SuPported by the strong contrOl ofeconomy, SingaPore goverment constructed a central public funds system, whileChile make a great success in practice when it introduced market mechanisminto the operaion of old-age security funds.) Gennn old-age security mode isa tyPical patly accumulate system,On the basis of the present situation of China and the advantage of old-agesecurity system leam from other countries, how to consmict one with Chinesecharacteristic which will be adaPted to China’s situation, this is an urgentproblem which needs resolving inimediately, this thesis tries