The fertility of a wheat male sterile line 337S was investigated in 4 consecutive years with 18 different sowing dates. Line 337S showed high sterility under both short daylength/low temperature and long daylength/high temperature during ear development. It has 2 time windows to be used as a male sterile line for hybrid seed production. Its fertility rate can be >50% with suitable sowing time; thus, it can be self-maintained as a male sterile line. Line 337S was reciprocally crossed with 7 common wheat varieties and the fertility of their F₁, F₂, and BC₁ hybrids was investigated at different sowing dates. The results showed that recessive nuclear genes controlled male sterility in 337S and no cytoplasmic effect was observed. All common wheat varieties were able to restore its fertility. The male sterility was controlled by a pair of recessive genes under short daylength/low temperature, but was governed by 2 pairs of recessive genes under long daylength/high temperature. This novel male sterile line provides a new tool for using heterosis in wheat.