Based on systems of semiconductor lasers with two mutual timedelayed couplings and three mutual timedelayed couplings, the influence of coupling delays and coupling strength to isochronal chaos synchronization was numerically studied. A thought that one coupling delay could be seen as feedback delays was presented in the system with two mutual timedelayed couplings. The condition and law for isochronal chaos synchronization was revealed in the system of semiconductor lasers with multiple mutual timedelayed couplings. The results show that the ratio 2 of two coupling delays is a basic condition to achieve isochronal chaos synchronization with high quality. Increasing coupling strength can improve the quality of isochronal chaos synchronization, and when the coupling strength is lower, the system with two mutual timedelayed couplings is much easier to achieve good isochronal chaos synchronization than system with three mutual timedelayed couplings.