The wide use of high baudrate and high-order modulation format signals makes coherent optical communication systems more sensitive to hardware impairment in the transceiver, so there is an urgent demand for corresponding impairment estimation scheme. This paper proposes a new joint estimation scheme for transceiver impairment based on digital signal processing, which can simultaneously monitor in-phase/quadrature (IQ) amplitude, phase imbalance, and time skew caused by the hardware imperfections of the optical transmitter and optical receiver. First, the Godard timing error detector and Gram-Schmidt orthogonalization method are used to estimate and compensate for the receiver impairment. Then, the maximum likelihood-based independent component analysis method and cascaded decision-direct least mean square (DDLMS) algorithm are used to achieve polarization de-multiplexing and carrier phase recovery which are insensitive to transmitter impairment. Finally, the transmitter impairment is estimated from the tap coefficients of DDLMS algorithm. The scheme achieves wide range impairment monitoring, which is attributed to polarization de-multiplexing and carrier phase recovery that are insensitive to the IQ of the transmitter. Simulation results demonstrate that the estimation ranges of the amplitude and phase imbalances of the proposed scheme are improved by about 100% and 33% compared with that of the conventional digital signal processing scheme, respectively.