To improve visual quality of weak target infrared images under the water,an enhancement method is proposed based on infrared radiation theory,edge analysis and transmittance estimation.Function expression for the original images about transmittance and optical path radiation are obtained by analyzing radiation theory.Coarse transmittance is gotten with dark channel prior,and fine transmittance is achieved based on edge weight analysis and guided filtering.Meanwhile,path radiation is also calculated with edge weight analysis.With the enhancement,the local contrast of potential target areas are highlighted well,enhancing the edge and texture feature.The testing results show that the proposed approach can fast obtain enhanced result with good visual effect,which lays a good foundation for target detection and recognition.