对无产权证房屋买卖合同不应直接认定为无效,而应适用我国合同法关于合同有效的规定或者第51条关于无权处分的规定。合同因解除条件成就而归于消灭时,已付房价款的返还、装修房屋所形成价值的返还属于不当得利返还。于此场合,不得适用过失相抵规则,除非守约方对此类返还选择了违约损害赔偿的请求权基础。这些返还与违约方应承担的违约损害赔偿并行不悖。 The contract of sale of property ownership certificates should not be directly invalidated, but should be applied to our contract law on the effective provisions of the contract or Article 51 of the provisions on the right to disposition. The contract due to the lifting of the conditions and achievements attributed to the destruction, the price has been paid back the refund, the value of the renovation of the housing formation of the return is unjust enrichment return. In this case, the rules of negligence should not be applied unless the contracting party has chosen the basis of the right of claim for breach of contract damages. These reparations go hand in hand with the breach of contract damages that the breaching party should bear.