The scheme of secure telemetry data transmitting system using in certain UAV system is discussed here. This encryption not only has strong security, but also can be easy realized, with few error-spreading and no message-spreading. Thinking of the error correction coding technique in this telemetry data transmitting system, the encryption technique and coding technique are tie in one by reasonable way, so both can behave in best performance. This scheme is very suitable for telemetry data format. Recent test-fly approves this scheme work well and reliably.