Using an isospin-dependent quantum molecular dynamics (IQMD) model, we study the 15C induced reactions from 30-120 MeV/nucleon systematically. Here the valence neutron of 15C is assigned at both 1d5/2 and 2s1/2 states respectively in order to study the density effect of reaction mechanism. It is. believed that the existent neutron halo structure at the 2s1/2 state of 15C will affect the light particle emission evidently.In our calculation, the different density distributions of 15C at two states are calculated by relativistic mean field (RMF) model and introduced in the initiation of IQMD model, respectively. It is found that some observables such as emission fragmentation multiplicity, emission neutron/proton ratio and emission neutrons'kinetic energy spectrum are sensitive to the initial density distribution.