The fuel consumption and emission of smalltype 4cylinder diesel engine were simulated and researched through the test according to the cylinder deactivation technology. The model was established with GTpower software and the influence of cylinder position on fuel consumption was simulated. Then the position of deactivating cylinder was determined by analyzing the factors such as heat loss. Experiments and combustion analysis were carried out by cutting off fuel or both fuel and air. The results show that the isovolumetric degree decreased after deactivating the cylinder. In addition, fuel consumption and NOx emission increase but the soot decreases. In the mode of cutting off fuel and air, the fuel consumptions of some test points decrease, but the NOx and soot emissions increase.