Our investigations into the water consumption patterns of maize (Zea mays L.) grown using surface drip irrigation with and without plastic mulching were based on three consecutive years (2014-2016) of field experiments in a typical area of northeastern China. We evaluated seasonal crop evapotranspiration (ETc) and how it was partitioned into soil evaporation (E-s) and plant transpiration (T-p) during the season. Development of crop coefficient (K-c) prediction models was based on the growth day (GD) and leaf area index (LAI) of the crop, as well as the growing degree-days of air (GDD(air)) and soil (GDD(soil)). Results showed that plastic mulching significantly reduced Es by 41.6 to 53.5 mm (p < 0.05) compared to not mulching, while it increased T-p by 23.2 to 40.4 mm (p > 0.05) for spring-planted maize. While plastic mulching normally reduced ETc during the crop growth period, the change was not significant (p > 0.05). The three-year mean K-c for the maize growth period declined by 3.0% under plastic mulching. The mean K-c was lower for the plastic mulching treatment than for the non-mulching treatment in both the early and late season, while it was slightly higher at mid-season. The three-year means of mid-season K-c (Kc-mid) under plastic mulching and non-mulching were 1.06 and 1.05 lower, respectively, than the FAO-56 recommended value. In addition, the K-c estimation model based on GDD(soil) achieved the best fitting accuracy. We recommend applying this GDD(soil) model to mulched drip irrigation of maize in northeastern China to obtain more accurate K-c estimation for optimizing and developing mulched drip irrigation in this region.