The AB cross-linked polymers (ABCPs) based on vinyl-terminated polyurethane [derived from polyurethane (PU) prepolymer with methacrylamide] and allyl novolac resin (obtained by substituting the hydrogen of hydroxy group of phenol in novolac resin with the allyl group) were synthesized. The PU prepolymer was composed of 4,4＇-diphenylmethane diisocyanate (hard segment) and poly(tetramethylene oxide) (soft segment). For these ABCPs, phase mixing was investigated and evaluated through dynamic mechanical analysis, differential scanning calorimetry, and transmission electron microscopy. The results indicated that the compatibility between PU and phenolic resin was improved, but there is no well-defined relationship in the mechanical properties.