The invention provides an engine oil cooler. The engine oil cooler comprises a main body, a guide-in channel used for guiding coolant of an engine into the main body, a guide-out channel used for guiding the coolant in the main body out, and a control mechanism matched with the main body, wherein the guide-in channel is composed of a cylinder cover guide-in channel body and a cylinder body guide-in channel body, and the control mechanism is triggered by the change of the temperature of the coolant in the guide-out channel to control alternate opening of the cylinder cover guide-in channel body and the cylinder body guide-in channel body. Due to the fact that the guide-in channel is divided into the cylinder cover guide-in channel body and the cylinder body guide-in channel body which are independent of each other and the control mechanism controls alternate opening of the cylinder cover guide-in channel body and the cylinder body guide-in channel body according to the temperature change of the guide-out channel, coolant used for achieving a required temperature can be obtained as much as possible during cooling of the engine oil cooler, and using performance and using effect are improved. The invention further relates to an engine cooling system provided with the engine oil cooler and a control method of engine cooling system.