In this paper, coal-based rotary kiln direct reduction-hydrogen reduction process was demonstrated to an efficient way to prepare the PMIP. Under the optimum conditions, a superior PMIP with 98.5% iron grade and only 0.31% H-2-loss can be achieved. Meanwhile, PMIP have the perfect physical properties of 2.45 g/cm(3) bulk density, 38 s.50 g(-1) flow rate and 6.40 g/cm(3) compressibility, which all meet the standard of MHF80.235 (first class goods). Moreover, the enhancing mechanism of PMIP properties was investigated as well, and the results show that the growth of metallic iron grains can obviously reduce the porosity and promote the densification of PMIP structure, which is beneficial for the bulk density and flow rate. This finding can point a new direction to improve the performances, including bulk density and by appropriately extending carbon reduction duration to promote the grain growth and improve the densification of PMIP structure. (C) 2020 Published by Elsevier B.V.y