Currently，little study has been carried out on the plate-fin heat exchanger with internal flow channel， and its heat dissipation power cannot be calculated accurately as its boundary conditions are be over-simplified． Therefore，a simulation analysis model of plate-fin heat exchanger with internal flow channel and a small wind tunnel experimental system was developed based on the interactions of cooling air，hot fluid and heat exchanger． The results show that，under the cooling conditions of 1m/s air speed and 25℃air inlet temperature，the heat dissipation power increases with mass volume of hot fluid，and will be stable after the mass volume reaches 3 L/min． The maximum deviation between the numerical analysis results and the experimental results is less than 5%． After validation，the effect of flow channel level on heat dissipation performance was investigated． The result shows that the heat exchanger with four-level internal flow channel is of best efficiency and temperature uniformity，but its highest temperature in internal flow channel is still lower than that of hot fluid inlet temperature 22 K，which demonstrates the necessity to take the interactions of cooling air，hot fluid and heat exchanger into consideration in simulation analysis．