Abstract: To solve the interference problem caused by the multiplexing of cell-free massive MIMO network resources in D2D communication, the joint pilot allocation and power control problem of cell-free massive MIMO systems coexisting with D2D communication are studied First, to suppress the interference of D2D users (DUEs) to cell-free users (CFUEs), an interference-assisted minimum mean square error (MMSE) detector was proposed; the uplink closure spectral efficiency expressions for DUEs and CFUEs based on the interference-assisted MMSE detection were derived for the imperfect channel state conditions. Second, to reduce the guide frequency pollution, for the guide frequency allocation problem, a guide frequency multiplexing method with the optimization objective of minimizing the sum of the system normalized channel estimation errors (NMSE) was proposed to assign guide frequencies to DUEs, and combined with a particle swarm algorithm based on for Tabu search to assign guide frequencies to CFUEs. For the data power optimization problem, the scheme of maximizing the minimum spectral efficiency in CFUEs under guaranteeing the quality of service of DUEs was proposed and solved by the bisection method. Simulation results show that the proposed joint guide frequency allocation and power control scheme based on interference-assisted MMSE detection effectively improves the total sum spectral efficiency of the system and the guide frequency overhead does not increase with the increase in the number of D2D.