The invention discloses a diesel engine oil tank with filtering and preheating functions. The oil tank comprises an oil tank body, an isolating box is arranged at the top end of the interior of the oil tank body in an isolated mode, and an oil inflow pipe is mounted on one side of the isolating box and communicates with the oil tank body; an oil pump is mounted at the top end of the isolating box, the input end of the oil pump communicates with the oil tank body through an oil delivering pipe, and the output end of the oil pump communicates with a connecting pipe; the oil delivering pipe is sleeved with a heating ring, and two filtering funnels are arranged on the section, between the heating ring and the oil pump, of the oil delivering pipe in a communicating mode; and filtering nets are mounted on the connecting positions of the two filtering funnels and the oil delivering pipe correspondingly. According to the diesel engine oil tank with the filtering and preheating functions, when diesel oil passes through the oil delivering pipe, the heating ring heats the diesel oil in the oil delivering pipe to preheat the diesel oil so as to enable the temperature of the diesel oil to rise, thus the diesel oil can be completely burned during compression ignition, and the utilization rate of the diesel oil is increased; and meanwhile, the filtering nets filter impurities in the diesel oil to enable the impurities in the diesel oil to be deposited in the filtering funnels, and the situation that the oil pipe of a diesel engine is blocked is avoided accordingly.