Abstract:Field distribution parameters (FDP),such as temperature,seepage and stress,are important in civil engineering. It is important to obtain the parameters by inversion of field measurement. According to the relationship between the parameters and acoustic velocity,field distribution parameters can be determined by acoustic velocity distribution which can be calculated by acoustic computer tomography (ACT). Considering of the characteristics of filed parameters distribution,smoothing operator (SO) is proposed in SIRT iterative process of ACT. SO is derived from the corresponding partial differential equation that introduces the contribution of adjacent cells into SIRT process and improves the inversion accuracy obviously. At last an example of frozen temperature field inversion is given to illustrate the effectiveness of the method.