Abstract: This experiment used the soybean cuhivars in the northern cold areas of Heilongjiang to explore the suitable flat planting density and a new density test method-the radiating circular flat sowing planting method. The results showed that： the two reference cuhivars in routine tests showed that with increasing density yield showed a decreasing trend .When the density of Heihe 43 was 300 000 / ha, the yield was the highest and the yield was decreased with the increase of planting density. When the flat sowing density of Dengke 1 were 30 000 plants/ha and 36 000 plants / ha, the yield were the highest. When the density was 42 000 plants / ha, the yield was the lowest. Circular radiation planting method and conventional test results had little difference, however, environmental conditions had larger effects on circular radiation planting method, in the aspect of determining the flat sowing suitable planting density, circular radiation planting test did not have a unified calculation method and can no t accurately determine the density of variety and need to be further improved.