Exploring the effects of film mulching and nitrogen (N) on crop transpiration ($E_t$), soil evaporation ($E_s$), crop actual evapotranspiration (${ET}_a$), and their relationships with yield and water use efficiency (WUE) is vital to improve understanding of crop water consumption and production. A 3-year (2017―2019) maize field trial was designed with three film mulching patterns (flat planting without mulching (FPNM), ridge-furrow with biodegradable film mulch over the ridge (RFBM), and ridge-furrow with plastic film mulch over the ridge (RFPM) as main plots and N application levels (0 and 180 kg N ha^–1) as subplots. The results showed that RFBM and RFPM increased $E_t$ more than FPNM when no N was applied. However, the $E_t$ increment for FPNM was higher than for RFBM and RFPM during the 2017 (dry) and 2019 (wet) seasons when N was applied. Both RFBM and RFPM decreased $E_s$, ${ET}_a$, and the total $E_s$ / ${ET}_a$ ratio compared with FPNM, regardless of N application, and improved yield and WUE when no N was applied across all three seasons. Applying N to RFBM and RFPM significantly improved yields in 2017 and 2018 (normal) seasons and increased WUE across all three seasons compared with FPNM. However, in 2019, maize yields were 4.68% and 4.48% higher in FPNM than in RFBM and RFPM when N was applied. Nitrogen mainly increased $E_t$ during the reproductive stage in FPNM and RFPM, but increased $E_t$ during the mature stage in RFBM. In contrast, N for three planting patterns decreased $E_s$ at the seeding and filling stages but increased $E_s$ at the jointing and mature stages during the 2017 and 2018 seasons. However, in the 2019 season, N application decreased $E_s$ in FPNM and RFBM, but increased $E_s$ in RFPM. N application also improved yield and WUE by 23.37–59.56% and 23.78–60.36% across the three seasons, respectively. Thus, RFBM and RFPM are recommended for maize production in northwest China, and RFBM with N application can replace RFPM in dry and wet seasons.