Becuase short parallel double-lines lines on the same tower are usually not transposition-erection, there is a problem of asymmetry of the line parameters and difficulty in estimating the parameters. To solve this problem, this paper proposes a parameter identification method based on an improved unscented Kalman filtering method for short parallel double-lines lines on the same tower. First, according to the characteristics of short-circuit parallel transmission lines on the same tower, the corresponding impedance models, admittance models, and measurement equations are established. Then, based on the measurement error corrections, the measurement values and error variance arrays are corrected online to compensate for the measurement noise. Compared with other parameter identification methods, the method takes into account the asymmetry of short line parameters, so it is more in line with the actual operation of the power grid, and the introduction of measurement error correction can further improve the accuracy and stability of parameter identification. Simulation results verify the effectiveness of this method. This work is supported by the National Natural Science Foundation of China (No. 51607112).