To finely describe the internal spatial structure characteristics of femtosecond laser filaments, the forward propagation process of ultrasound induced by optical filaments is first simulated in fine detail, and then different photoacoustic tomography image reconstruction algorithms, such as the universal back projection algorithm (UBP), delay and sum (DAS) and superiorized photo-acoustic nonnegative reconstruction algorithm (SPANNER), are used to perform reverse reconstruction image of filaments. The results theoretically verify the feasibility of using a multiple linear array detection to reconstruct the axial r-z section of a single filament and multiple filaments. The results show that the maximum frequency of the ultrasonic signal induced by a single filament and multiple filaments at a detection distance of 3 mm is approximately 5 MHz. Photoacoustic tomography can accurately retrieve the single filament position and r-z section profile, but the reconstruction effects of different image reconstruction algorithms are quite different. The UBP algorithm has obvious artifacts in the reconstruction of filaments; the DAS algorithm overestimates the diameter of light filaments due to the "finite aperture effect"; the SPANNER has the best effect on multiwire image reconstruction because it uses optimal theory to improve the nonlinear conjugate gradient operator and realize nonnegative and anisotropic total variational regularization, which can effectively avoid noise interference. The results of this study have certain reference value for revealing the structural characteristics of laser filaments and promoting the laser filamentation based atmospheric application research.