A method for controlling a cooling system of a hybrid vehicle comprising at least one combustion engine and one electric motor , the hybrid vehicle being able to assume the following operating modes: - an electric mode, wherein the vehicle is propelled and/or towed by the electric motor without the intervention of the combustion engine; - a thermal mode wherein the vehicle is towed and/or propelled solely by means of the combustion engine without the intervention of the electric motor; - a hybrid mode wherein the vehicle is towed and/or propelled simultaneously by means of combustion engines and electric motors; the cooling system comprising at least: - a high-temperature cooling circuit for cooling the combustion engine and a low-temperature cooling circuit for cooling the electric motor and an associated high-voltage battery , and - a coolant transfer circuit connecting the high-temperature cooling circuit and the low-temperature cooling circuit and comprising regulating means for controlling the circulation of coolant in the transfer circuit , the method for controlling the cooling system in electric mode comprises at least: - an initialization step "E0" consisting in checking the operating parameters linked to driving in electric mode, such as the charge of the high-voltage battery or that the temperature of the battery is higher than the minimum usage temperature (Tu-min), the "E0" initialization step being implemented in particular when the hybrid vehicle is started up, - a step "E1" consisting in determining whether the coolant present in the high-temperature cooling circuit is at a temperature below or above an operating limit temperature (TFmax) of the low-temperature cooling circuit ; and - when the temperature of the coolant in the high-temperature cooling circuit is below the operating limit temperature (TFmax) of the low-temperature cooling circuit , a step "E2" consisting in controlling said means for regulating the transfer circuit to assume the open position. - an electric mode, wherein the vehicle is propelled and/or towed by the electric motor without the intervention of the combustion engine; - a thermal mode wherein the vehicle is towed and/or propelled solely by means of the combustion engine without the intervention of the electric motor; - a hybrid mode wherein the vehicle is towed and/or propelled simultaneously by means of combustion engines and electric motors; - a high-temperature cooling circuit for cooling the combustion engine and a low-temperature cooling circuit for cooling the electric motor and an associated high-voltage battery , and - a coolant transfer circuit connecting the high-temperature cooling circuit and the low-temperature cooling circuit and comprising regulating means for controlling the circulation of coolant in the transfer circuit , - an initialization step "E0" consisting in checking the operating parameters linked to driving in electric mode, such as the charge of the high-voltage battery or that the temperature of the battery is higher than the minimum usage temperature (Tu-min), the "E0" initialization step being implemented in particular when the hybrid vehicle is started up, - a step "E1" consisting in determining whether the coolant present in the high-temperature cooling circuit is at a temperature below or above an operating limit temperature (TFmax) of the low-temperature cooling circuit ; and - when the temperature of the coolant in the high-temperature cooling circuit is below the operating limit temperature (TFmax) of the low-temperature cooling circuit , a step "E2" consisting in controlling said means for regulating the transfer circuit to assume the open position. <EOS>