Drip irrigation with film mulching has been widely used in crop cultivation. Film mulching can change surface optical properties, including reflectance, absorption, and emissivity, which will affect the energy distribution in the farmland. It is necessary to study the water and heat transport and its influence factors in drip irrigated field with film mulching. The quantification of water and heat transfer process of the farmland is of great significance for agricultural water management and irrigation schedule formulation. Based on the measured data with Bowen ratio system and meteorological station, the water and heat flux variation and its response to environmental factors were studied in drip irrigated purple potato field with film mulching. The results indicated that latent heat flux was the main part of energy expenditure in drip irrigated purple potato field with film mulching during the whole growth period. Sensible heat flux and soil heat flux accounted for a relatively small proportion. During the whole growth period, the proportion of latent heat flux, sensible heat flux and soil heat flux was 69.12%, 25.14% and 6.57%, respectively. Under different weather conditions, the magnitude and range of sensible heat flux were smaller than that of latent heat flux. Latent heat flux had the most significant response to rainfall and irrigation. The influence of rainfall on latent heat flux was greater than that of irrigation. Net radiation and air temperature had great impact on latent heat flux, while the effects of surface soil temperature and wind speed had low impact. Various environmental factors affected the latent heat flux directly or indirectly. The research results can deepen the understanding of water and heat transfer in drip irrigated purple potato farmland under film mulching, and provide theoretical basis for efficient water use of crops.