A method for manufacturing a silicon nitride thin film comprises a step of charging silane, ammonia gas and nitrogen gas at an environment temperature below 350° C. to produce and deposit a silicon nitride thin film, wherein a rate of charging silane is 300-350 sccm, a rate of charging ammonia gas is 1000 sccm, a rate of charging nitrogen gas is 1000 sccm; a power of a high frequency source is 0.15˜0.30 KW, a power of a low frequency source is 0.15˜0.30 KW; a reaction pressure is 2.3˜2.6 Torr; a reaction duration is 4˜6 s. The above method for manufacturing a silicon nitride thin film provides a preferable parameter range and preferred parameters for generating a low-stress SIN thin film at low temperatures, achieves manufacture of a low-stress SIN thin film at low temperatures, and thus, better satisfies the situation requiring a low-stress SIN thin film.