In order to figure out the impact of climate warming on crop planting areas, this paper used grid data to analyze agricultural heat resources in China based on methods of Sliding Mean Temperature of Five Days, accumulated anomaly, Manner-Kendall test and multiple regression interpolation. The results showed that: (1) The effective accumulative temperatures (≥5 ℃ and ≥10 ℃) show an overall upward trend, and the accumulative temperature of ≥5 ℃ is more remarkable. The southern region has the highest inclination rate, followed by the northern region, and the Qinghai-Tibet Plateau has the smallest, while the cumulative temperatures of the Qinling-Daba mountains show a decreasing trend. (2) The effective accumulated temperatures (≥5 ℃ and ≥10 ℃) present a similar spatial distribution, namely, the accumulated temperature varied with latitude from south to north and varied with altitude from east to west. The eastern and central regions of China are obviously affected by latitude, while the western region is affected more by altitude than latitude. The area suitable for planting chimonophilous crop is larger than that suitable for thermophilic crop. (3) The effective accumulated temperatures of both ≥5 ℃ and ≥10 ℃ mutated in 1997, and both of their boundaries show a tendency toward northward and high altitude. The cumulative temperature increment in the south is larger than that in the north. The Qinghai-Tibet Plateau and mountain areas with high altitude have the smallest increase, while cumulative temperature increment is negative in the Qinling Mountains. (4) The initial days (closing day) of the effective accumulated temperature (≥5 ℃ and ≥10 ℃) presented an overall phenomenon of advance (delay), and the number of advance (delay) days is mostly within 0-10 days. Both of their durations increased overall after mutation. The number of initial days (closing day) in advance (delay) is the largest in the Qinghai-Tibet Plateau.