Usually, the practical analysis states of an imaging polarimeter need to be calibrated, with a set of standard polarization states, for the accurate reconstruction of Stokes parameters. However, it is challenging to get the standard elements for the polarimetric calibration. In this Letter, an iterative reconstruction method is presented for the first time, to the best of our knowledge, to recover the polarization parameters from the data acquired by linear Stokes polarimeters without polarimetric calibrations. Inspired from phase-shifting interferometry, the method employs two least squares iterative procedures and requires no extra element for assistance. Experimental results show that the iterative method is more robust to noise perturbation and gets higher precision compared with the calibration method with reference polarization states.