In this study, chitosan (CS), polyvinylpyrrolidone (PVP), polydopamine (PDA), and tungsten trioxide are compounded via melt blending to prepare a CS/PVP/PDA/WO3 composite mulch. The morphological characteristics, thermogravimetric analysis, transmission performance, photothermal performance, and degradation performance of the mulch film and the effect of the CS/PVP/PDA/WO3 composite mulch film on the growth of Dianthus chinensis L. and cucumber seeds are studied. The results show that the CS/PVP/PDA/WO3 film exhibits a good thermal stability, biodegradability, UV resistance, photothermal conversion ability, and transmittance. Evaluation of the effect of this mulch film on the growth of crops shows that the film can promote the germination of seeds and increase the seedling growth rate. [ABSTRACT FROM AUTHOR]