ABSTRACT Combined with visualization experiments, a square cavity reciprocating oscillation system is built based on CA6110 diesel engine to study heat transfer enhancement mechanism and explore a more efficient cooling method. Influences of liquid fill ratio, engine speed, and surface property on flow pattern and heat transfer characteristics are studied. Four surfaces are prepared. Results show that heat transfer performs the best with 50% liquid fill ratio and it is improved with increasing engine speed. Polished surface performs the worst, then super-hydrophilic surface and microstructure surface perform better, and microstructure super-hydrophilic surface performs the best with an 66% increase of average heat transfer coefficient.