Porous inorganic polymers with good compressive strength can be applied in various applications. In order to obtain porous inorganic polymers with good compressive strength, fibers addition and carbonation curing was employed in porous inorganic polymers producing process. With the addition of 6 mm 2 wt% PVA fibers and 12 hours’ carbonation curing, the inorganic porous polymers with 2.0 MPa compressive strength and 540 kg/m3 density were successfully produced. X-ray diffraction, thermogravimetric analysis, fourier transform infrared spectroscopy and scanning electron microscope - energy dispersive X-ray spectroscopy were applied to explore the reinforcement mechanism of porous inorganic polymers. It suggested that the synergistic compressive strength reinforcement mechanism involved in both physical and chemical changes. Physically, fiber addition promoted bridging effect, restricted crack expansion and accelerated carbonation process. Chemically, the formation of CaCO3 through carbonation reaction filled in the voids of the matrix and facilitated network structural, enhancing densification and overall strength.