The invention belongs to the field of solar total radiation measuring equipment, and particularly relates to a solar radiation measuring device for a solar water heater. The solar radiation measuringdevice comprises a total radiometer, an angle calibration mechanism, an angle adjusting mechanism and a base, wherein the total radiometer is arranged on the base, the base is connected with the totalradiometer through the angle adjusting mechanism, and one side of the total radiometer is connected with the angle calibration mechanism; when the solar water heater is used, the device is erected beside the solar water heater, then a reference plate is moved and placed on a heat collecting tube of the solar water heater, and a telescopic link is adjusted until a bottom surface of the reference plate is completely contacted with the heat collecting tube. At this time, since the bottom surface of the reference plate is parallel to a horizontal rod, that is, the bottom surface of the referenceplate is parallel to the total radiometer, an inclination angle of the total radiometer is completely consistent with that of the heat collecting tube. The solar radiation measuring device is ingenious and light in design structure, and low in cost, the angle of the total radiometer can be quickly adjusted by only flatly laying the reference plate, the adjusting is precise, and a measuring resultis more accurate.