It is very important for temperature field testing in laser processing. Temperature field is an important parameter which affects the quality of laser processing. In order to control profile of laser molten pool and improve process design, precision and quality in laser processing, it is very necessary to study the temperature distribution. The image processing based on digital signal processor (DSP) was presented. It was used to measure the temperature field of laser molten pool. A new method of image processing was developed with DSP as personal computer, without PC. It makes the system become simple and efficient. It shows that some important informations included 2D morphology and size, numerical value distribution and dynamic characteristics of temperature field in laser molten pool can be obtained. In the future, it will be much more available on online measurement and feedback control in laser processing.