The underwater acoustic channel poses many obstacles to sound propagation. Especially, when sound propagates over a long range (>80 Km), it will always encounter an extremely complicated environment with multi sound-speed profiles and water depth varying with range. In such a case, the channel characteristics vary a lot from the flat bottom one. Based on the analysis of optimum propagation frequence, the paper presents the transmission properties of continuous wave (CW) and pulse under a complex condition with multi sound-speed profiles and sloping sea bottom, analyzes the long range transmission effects due to the locations of the transmitter and receiver. Such results can benefit the design of long range underwater acoustic telemetry system.