Microwave treatment can cause macroscopic cracks in wood. The effects of moisture content,microwave powers, and treatment times on macroscopic cracks in the cross section of Mongolian scotch pine（Pinus sylvestris var. mongolica Litv.） after microwave treatment were investigated. Results showed that the moisture content and microwave powers had a significant influence on the microwave energy absorption by the Mongolian scotch pine samples. The number of cracks in the cross section of Mongolian scotch pine samples and crack area ratio reached the largest at 40%～60% of the moisture content, 140 k W of the microwave power and 120 seconds of the treatment time. It was suggested that different microwave treatment processes should be chosen accordingly based on the application of materials.