The invention relates to an automatic calibration system of a measuring cylinder. The system comprises a computer, measuring cylinder system detection software, an automatic water injection mechanism,a weighing mechanism, an image collection mechanism, a motion mechanism, a light source and a temperature and humidity sensor, wherein the measuring cylinder system detection software is installed inthe computer, the computer sends a command through a data line to control the automatic water injection mechanism, the weighing mechanism, the image collection mechanism, the motion mechanism, the light source and the temperature and humidity sensor, the image collection mechanism is installed on the motion mechanism, and the motion mechanism can drive the image collection mechanism to move. Through the system, the liquid level position of the measuring cylinder can be recognized through a vision technology, the position relation between a crescent surface formed by water in the measuring cylinder and a target scale line can be obtained reliably in real time, and calibration is completed by controlling on/off of a water pump according to the position relation and reading data of the temperature and humidity sensor and through cooperation of other parts, so that detection speed is high, and detection precision is high.