The invention discloses a measurement instrument of the moisture regaining rate of cotton wool, which comprises a single chip computer, a battery, a temperature sensor, a direct-current voltage-stabilizing measurement device, an operation component and an instrument panel, wherein the temperature sensor is connected with the single chip computer, the direct-current voltage-stabilizing measurementdevice is connected with the battery, the operation component is used for inputting a command to the single chip computer, and the instrument panel is used for installing the operation component. Thetemperature sensor adopts a digital type temperature sensor, the digital type temperature sensor is embedded on the instrument panel, and an induction opening of the sensor is exposed to outside and is aligned with the external surface of the instrument panel. Thus, on one hand, the sensor can be communicated with outside in an unobstructed way, and the outside temperature is accurately measured.On the other hand, the defect of easy damage when bulging can be avoided. The single chip computer and the battery are connected by an electronic switch, the operation component is a key, the instrument panel is a full key type panel, and the panel has beautiful appearance and simple and convenient operation.