Crosstalk is one main problem which leads to false distance measurement and reduces work efficiency of ultrasonic range sensor systems in mobile robots. The reason which results in ultrasonic crosstalk is briefly analyzed. To enhance the SNR (Signal Noise Ratio) and work efficiency, different methods used to avoid ultrasonic crosstalk have been put forward in the past decade. Such representative methods are classifled into two categories, which are called heuristic soft-rocessing strategy and hardware based coding strategy in this paper. The advantage and disadvantage of each method are analyzed. Suggestions and comments on designing non-crosstalk ultrasonic range system are proposed at the end.