A method for controlling a plug-in hybrid electric vehicle, comprising: setting, by a controller, an initial distance until charge; calculating, by the controller, a current DUC by subtracting a travel distance of the plug-in hybrid electric vehicle from the initial DUC after the initial DUC is set; calculating, by the controller, a current distance to empty based on a current state of charge of a battery; comparing, by the controller, the current SOC of the battery with a reference SOC; comparing, by the controller, the current DUC with the current DTE when the current SOC is greater than the reference SOC; determining, by the controller, whether a high speed condition or a high load condition is satisfied when the current DUC is greater than the current DTE; setting, by the controller, a driving mode of the plug-in hybrid electric vehicle to be a charge sustaining mode when the high speed condition or the high load condition is satisfied; characterized in that the method further comprises the following steps: comparing, by the controller, demand power of a driver with a first predetermined power when the driving mode of the plug-in hybrid electric vehicle is set to be the CS mode; starting, by the controller, an engine when the demand power of the driver is greater than the first predetermined power; and comparing, by the controller, the demand power of the driver with a second predetermined power when the driving mode of the plug-in hybrid electric vehicle is set to be a charge depleting mode; and starting, by the controller, the engine when the demand power of the driver is greater than the second predetermined power, wherein the first predetermined power is less than the second predetermined power. setting, by a controller, an initial distance until charge; calculating, by the controller, a current DUC by subtracting a travel distance of the plug-in hybrid electric vehicle from the initial DUC after the initial DUC is set; calculating, by the controller, a current distance to empty based on a current state of charge of a battery; comparing, by the controller, the current SOC of the battery with a reference SOC; comparing, by the controller, the current DUC with the current DTE when the current SOC is greater than the reference SOC; determining, by the controller, whether a high speed condition or a high load condition is satisfied when the current DUC is greater than the current DTE; setting, by the controller, a driving mode of the plug-in hybrid electric vehicle to be a charge sustaining mode when the high speed condition or the high load condition is satisfied; characterized in that the method further comprises the following steps: comparing, by the controller, demand power of a driver with a first predetermined power when the driving mode of the plug-in hybrid electric vehicle is set to be the CS mode; starting, by the controller, an engine when the demand power of the driver is greater than the first predetermined power; and comparing, by the controller, the demand power of the driver with a second predetermined power when the driving mode of the plug-in hybrid electric vehicle is set to be a charge depleting mode; and starting, by the controller, the engine when the demand power of the driver is greater than the second predetermined power, wherein the first predetermined power is less than the second predetermined power.