A new blending method for the preparation of a series of macroporous open‐cell polyvinyl formaldehyde (PVF) foams is reported here. Mechanism of foam‐formation was detailedly analyzed and it was found that the addition of polyvinyl alcohol (PVA) with a low degree of polymerization was important and crucial for the formation of PVF foams. Further, the addition of PVA with a low degree of polymerization is beneficial for the improvement of water solubility. The structures and properties of PVF foams were investigated by Fourier transform infrared (FTIR), scanning electron microscope (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The macroporous open‐cell PVF foams had a pore size ranging from 120.88 to 16.16 μm with an increased degree of acetalization and the water absorption capacity increased with the addition of PVA with a low degree of polymerization. PVF foams generally have higher thermal stability because of their cross‐linked network structure. The highest water absorption capacity of the PVF foam obtained presently can reach up to 960 wt%, which is much higher than most PVF foams reported so far.