Maize is one of the main grain crops in China, and three provinces of Northeast China are the main areas of planting spring maize. The study on the effects of climate warming on spring maize and the adaptation countermeasures is important for national food security. In this paper, daily time series of air temperature during the past 50 years (1961-2010) and the next 20 years (2021-2040) under RCP 4.5 scenario at 71 stations were jointly used to study the spatio-temporal characteristics of heat resources and spring maize cultivars in Northeast China. At the same time, the adaptation countermeasures under RCP 4.5 scenario are discussed. Results show that in the next 20 years, the first date of air temperature ≥10 ℃ stably will be gradually earlier, and the end data of air temperature ≥10 ℃ stably and the first frost date will be later in Northeast China. Therefore, the durative days and accumulated air temperature ≥ 10 ℃ stably will increase accordingly. The maximum fluctuations of heat resources locate in Sanjiang Plain, where the first date of air temperature ≥10 ℃ stably shift 8 days earlier, and the first frost date are 10 days later. Correspondingly, the durative days and accumulated air temperature ≥10 ℃ stably increase about 15 d and 300 ℃ · d, respectively. In the next two decades, the northern boundaries of different spring maize cultivars will move to north and east faster than in the past 50 years. Till 2030s, the north boundary of the mid-late spring maize will expand to 49°32′N, and the east boundary will be at 135°E based on RCP 4.5 scenario. If the planting system is the same as current in 2030s, the sowing date can be 16-20 days earlier or later in Songnen Plain, and be 8-12 days in Sanjiang Plain, and be less than 8 days earlier or later in the coastland of the south region. The alternative countermeasure is to move different spring maize cultivars northward and eastward when climate become warming. If so, the north boundaries of late maize, mid-late maize, and mid maize will move northward about 2°13′N, 1° 08′N and 3°N to current boundaries in Northeast China.