[Objective] The aim was to explore application effects of truly biodegradable mulch in farmlands and provide data support for large area spreading on southern potato fields. [Method] The field plot experiments were conducted to investigate mulch film's weight loss and the effects of using truly biodegradable mulch film on potato yield and agronomic characters. [Result] The emergence rates of truly biodegradable mulch film and black plastic mulch film kept 9.71% and9.27% higher compared with the open field, and yield increased by 30.84% and36.81%. In the potato harvest period, the truly biodegradable mulch films already broke, and mulch film's weight loss rate was 58.62%. It can be completely degraded in the field after some time, and following crops would not be affected. [Conclusion] Truly biodegradable mulch performs significantly in increasing yield and keeps higher in weight-loss rate, so that it has a promising future.