Soybean is a typical short-day thermophilic crop and the sensitivity to photothermal environments determines the geographic adaptablity of soybean varieties. To further understand the photothermal responses, 282 Chinese accessions in mini core collection (MCC) were planted under both Spring and Summer cropping seasons in Jining, Shandong province of China. Photothermal comprehensive response sensitivity (PCRS) of the MCC was calculated based on the days from emergence to the beginning bloom (R1). The results showed a broad range of variations in PCRS and growth periods among the MCC germplasm. PCRS increased along with the maturity groups of MCC. PCRS values of the major soybean ecotypes was ordered as follows: autumn-sowing soybeans > summer-sowing soybeans > spring-sowing soybeans. Based on the PCRS values, the Chinese soybean MCC accessions were classified into three classes: sensitive, medium and insensitive in photothermal sensitivity. A larger proportion of the spring-sowing and summer-sowing varieties showed medium-sensitive, while 63.6% of the autumn-sowing varieties were found to be photothermal-sensitive. The sensitive germplams belonged mainly to MGIII or above (later), and the medium-sensitive and insensitive germplasms covered all maturity groups (MGs). MG value of a given variety is highly related to its PCRS, indicating that MG is a simple and reliable index to express the comprehensive response of soybeans. The gained results will be helpful to understand the photothermal characteristics of soybean germplasm in China and provide a theoretical basis, in order to explore and utilize the photo-insensitive germplasm in future breeding for widely-adapted soybean varieties.