Abstract: A gas-gas heat exchanger (GGHE) was designed and its working process was introduced in this paper. Based on the numerical method, a commercial prototype of GGHE was worked out and manufactured, and its performance was tested. Polypropylene (PP) plastic material was used to make the heat transfer fins and the counter flow of hot and cold gases in GGHE was achieved. The calculation results showed that there was a positive correlation between the quantity of heat-transfer and air volumes, and the efficiency of heat-transfer increased with rise of hot air volume as well. The calculated heat-transfer efficiency was 0.55-0.75, 0.6-0.8 when hot air volume was 4 475 , 7 800 m3/h, respectively. Meanwhile the efficiency of measured heat-transfer was 0.45-0.7, 0.65-0.9 while hot air volume was 4 475, 7 800 m3/h, respectively. The experimental values matched with calculated ones, this indicated that the PP GGHE had good heat-transfer performance and the design of GGHE was reasonable.