For the promising next-generation thin-film solar cells, Cu2SnS3 (CTS) solar cells still suffer from low open circuit voltage (VOC) and so resulting an unsatisfactory power conversion efficiency. Herein, Ag was introduced in solution-processed CTS thin films via adding AgNO3 into precursor solution for photovoltaic devices. Compared with CTS, the VOC deficit for CuxAg(2-x)SnS(3) (CATS) based cells could be effectively reduced for about 10 mV, together with the increased short circuit current density (JSC) and fill factor (FF), a power conversion efficiency of 3.99% was achieved. Such improved performance of CATS cells could be attributed to the improved crystallization, reduced shunting channels and the decreased band-gap of CATS films.