A method of terminal PTT registration based on CDMA trunking system, comprising: Step S102, after a PTT terminal is powered and a normal CDMA registration flow is completed, the value of a PTT registration message counter of the PTT terminal is initialized; Step S104, the PTT terminal initiates a registration to a dispatching server and sends a PTT registration message to a base station on a control channel through the PTT registration message; Step S106, after having sent the PTT registration message, the PTT terminal starts a PTT registration timer of the terminal and waits for a registration response message from the base station; Step S108, upon having received the PTT registration message of the PTT terminal user, the base station sends to the terminal a registration response message containing answer information; Step S110, if the registration response message received by the PTT terminal is a PTT registration acceptance message of the base station, then it goes to Step S114; if the registration response message received by the PTT terminal is a PTT registration refusal message of said the base station, then it goes to Step S118; if the PTT terminal has not received the response message from the base station when the PTT registration timer expires" it goes to S112; Step S112, the value of the PTT registration message counter is assigned by subtracting the current value of the registration message counter by 1 wherein if the value of the PTT registration message counter is greater than 0, then the PTT terminal returns to S104, re-sending the PTT registration message to the base station, otherwise it turns to S116; Step S114, the registration succeeds and the PTT terminal shuts down the PTT registration timer, finishing the registration; Step S116, the registration does not succeed and the PTT registration timer is shut down, finishing the registration; and Step S118, the registration is failed and the PTT registration timer is shut down, finishing the registration. Step S102, after a PTT terminal is powered and a normal CDMA registration flow is completed, the value of a PTT registration message counter of the PTT terminal is initialized; Step S104, the PTT terminal initiates a registration to a dispatching server and sends a PTT registration message to a base station on a control channel through the PTT registration message; Step S106, after having sent the PTT registration message, the PTT terminal starts a PTT registration timer of the terminal and waits for a registration response message from the base station; Step S108, upon having received the PTT registration message of the PTT terminal user, the base station sends to the terminal a registration response message containing answer information; Step S110, if the registration response message received by the PTT terminal is a PTT registration acceptance message of the base station, then it goes to Step S114; if the registration response message received by the PTT terminal is a PTT registration refusal message of said the base station, then it goes to Step S118; if the PTT terminal has not received the response message from the base station when the PTT registration timer expires" it goes to S112; Step S112, the value of the PTT registration message counter is assigned by subtracting the current value of the registration message counter by 1 wherein if the value of the PTT registration message counter is greater than 0, then the PTT terminal returns to S104, re-sending the PTT registration message to the base station, otherwise it turns to S116; Step S114, the registration succeeds and the PTT terminal shuts down the PTT registration timer, finishing the registration; Step S116, the registration does not succeed and the PTT registration timer is shut down, finishing the registration; and Step S118, the registration is failed and the PTT registration timer is shut down, finishing the registration.