Abstract: Measuring temperature distribution of laser penetration welding keyhole is one of the important ways to study the foundational theory of keyhole.The object is to get the 2-D temperature distribution of plasma in non-symmetry case,dividing one dimension spectrum information into symmetry and non-symmetry part by variable separation approach,computing plane 2-D distribution of antimere by numerical method based on Abel transform,the plane 2-D distribution in non symmetry case can be obtained.A hypothetical function is calculated with this method,error analysis proves that it describes real distribution for small global error accurately.It is important for the study of the foundational theory of the laser penetration welding keyhole.