An engine system having two cooling loops may include a first coolant loop in which a first coolant circulates through an engine and a first radiator, a second coolant loop in which a second coolant circulates through a water-cooled intercooler and a second radiator, a first branch line that branches from one side of the first coolant loop, a second branch line that branches from one side of the second coolant loop, a mixture line allowing the first coolant and the second coolant to be mixed to flow therein, and branching to the first coolant loop and the second coolant loop, a temperature adjusting valve configured to control a temperature of the mixture coolant flowing in the mixture line, and a mixture coolant line allowing the mixture coolant to flow, and branching to the first coolant loop and the second coolant loop.