Disclosed is a transmit method based on satellite massive Multiple-Input Multiple-Output (MIMO) integrated sensing and communication, where a satellite end is equipped with a massive MIMO array to implement an integrated sensing and communication system. The satellite end sends a communication signal to multiple user terminals based on statistical properties of electromagnetic wave propagation, and detects multiple targets simultaneously, thus realizing simultaneous communication of the satellite end with the user terminals and sensing for the targets. The present disclosure fully utilizes the spectrum resources, implements a flexible switch between wireless communication and target sensing functions based on a satellite, and mitigates the effects of the beam squint on system performance, thus greatly improving communication performance and radar resolution and being applicable for construction of an integrated network of space, air, ground and sea to achieve global coverage.