The multi-conjugate adaptive optics (MCAO) can effectively reduce the disturbance of turbulent atmosphere. For the design and performance optimization of MCAO technology, it is necessary to measure the atmospheric turbulence profiles of the site. The inversion linear equations of the methods based on differential image motion variance or covariance of extended object are obtained through discretization. The discretization error causes the effective field of view (FOV) not to be very wide. A small FOV limits the number of equations, resulting in turbulence profile inversion results being affected by motion variance or covariance measurement errors. In this paper, taking the PML method as an example, we propose a layer integral coefficient matrix method. This method obviously reduces the discretization error, greatly improves the range of observation FOV, reduces the influence of the covariance error on the measurement results, and improves the accuracy of the turbulence profile inversion. The simulation results show that the FOV of the PML method using layer integral coefficient matrix can reach 400″, and the measurement error is also greatly reduced.