A machine tool collision avoidance method includes: loading multiple processing codes; simulating multiple path traces corresponding to the processing codes; estimating multiple execution periods for running the path traces; selecting the shortest execution period from the execution periods; determines whether the distance between the trace point points on any two of the path traces is less than a safety distance within the shortest execution period; if the distance between a first trace point on a first path trace and a second trace point on a second path trace is less than the safety distance, estimating a first time point at which a first turret runs to the first trace point and a second time point at which the second turret runs to the second trace point; generating a collision warning if the difference between the first time point and the second time point is lower than a tolerance value.