  We develop an efficient method based on the linear regression algorithm to
probe the cosmological CPT violation using the CMB polarisation data. We
validate this method using simulated CMB data and apply it to recent CMB
observations. We find that a combined data sample of BICEP1 and BOOMERanG 2003
favours a nonzero isotropic rotation angle at $2.3\sigma$ confidence level, ie,
$\Delta\alpha=-3.3 \pm1.4$ deg (68% CL) with systematics included.
