Increasing the income of low-income groups is an important part of “solidly advancing common prosperity”，and implementing social assistance system is a crucial way to increase the income of low-income groups. This article finds that the standards of social assistance in Beijing have been steadily promoted，and the mechanisms of social assistance have been continuously improved，but there are still practical problems such as the overall narrowness of assistance and the weak service guarantee. In the future，we need to improve the social assistance policy system，explore the assistance mechanisms for people in relative poverty，increase the accuracy in implementing classified assistance，expand the coverage of social assistance，strengthen the comprehensive assistance and guidance effect of social assistance，and encourage the active participation of social forces.