The invention relates to a power module and a photovoltaic grid-connection inverter using the power module. The photovoltaic grid-connection inverter comprises a machine cabinet and the power module arranged inside the machine cabinet. The power module comprises a machine box and a bus capacitor group arranged inside the machine box, a heat radiator and an IGBT module. The machine box is provided with ventilation and heat radiation channel arranged from the top to the bottom and installation cavities arranged at the left side and the right side of the heat radiation channel for the bus capacitor group and the IGBT module to be installed therein. The air inlet mouth of the heat radiation channel is located at the bottom of the machine box while the air outlet mouth is arranged at the top of the machine box. According to the invention, the heat radiation of the power module starts from the inverter globally, using the mouth at the bottom to incorporate air and the mouth at the top to discharge air. The heat radiation channel penetrates the machine box from the top to the bottom; and the air inlet mouth at the lower end of the machine box faces right the electric reactor below the inverter. The air outlet mouth at the upper end of the machine box and the air inlet mouth of the big fan at the top of the inverter form a heat radiation channel that is sealed circumferentially. The heat generated from the electric reactor and the IGBT module is discharged out of the machine cabinet through the heat radiation channel. And the heat radiation effect is good.