Inorder to compare of the synchronization error affect on location accuracy between TOA(Time Of Arrival) and TDOA(Time Difference Of Arrival) schemes ,The synchronization error’s components were analyzed and the clock offset contained measurements model is established, the TOA and TOA/RSS(Received Signal Strength) schemes’ modified Cramer-Rao bound (MCRB) are derived, compare with the TDOA and TDOA/RSS schemes’s Cramer-Rao bound respectively. It’s shown that the transmitter’s clock offset are also the unknown variable in the new observation equation, it can be solved in the TOA scheme to eliminate part of synchronization error; the TDOA scheme sacrifice one measurement to subtract the transmitter’s clock offset from unknown variables lead synchronize requirements can be relaxed. The theoretical derivation and the computer simulation both show that the MCRB are the same for TOA and TDOA schemes and the MCRB are the same for TOA/RSS and TDOA/RSS hybrid schemes when using the same sensor array and the same amount synchronization error were introduced. Especially,the hybrid schemes improve the short distance location accuracy.