The invention discloses a method for measuring and calculating the gas turbine energy loss rate in a united co-production unit. The method comprises the following steps that thermodynamic parameters of a gas turbine in the united co-production unit and the power generating capacity of the gas turbine are obtained; a solution equation is utilized to obtain a data result; then, the power generating capacity of the gas turbine is obtained to establish gas turbine energy balance relation; according to the gas turbine energy balance relation, an energy loss value of the gas turbine is obtained; according to a heat value brought by natural gas, a discharge smoke heat value of the gas turbine and an energy loss value of the gas turbine, the gas turbine energy loss rate is obtained. By adopting the method, the gas turbine energy balance relation of the gas turbine is established by obtaining the relevant thermodynamic parameters and the power generating capacity of the gas turbine in the united co-production unit, and finally the energy loss rate of the gas turbine is measured and calculated. The measuring and calculating method is accurate, simple and convenient, and the problem that at present, no gas turbine energy loss rate measuring and calculating method is disclosed yet and accordingly measurement and calculation of heat consumption sharing, power generation and heat supply subitem indexes of the united co-production unit are influenced is solved.