A negative working thermally stable and photosensitive polymer 3 based on poly(2-hydroxy-6-methylphenol-co-2, 6-dimethylphenol), 2, 6-bis(hydroxymethyl)-4-methylphenol (BHMP) as a cross-linker, and a photoacid generator diphenyliodonium 9, 10-dimethoxyanthracene-2-sulfonate (DIAS) has been developed. Polymer 3 was prepared by oxidative coupling polymerization of 2-(tetrahydropyran-2-yl)oxy-6-methylphenol 1 with 2, 6-dimethylphenol 2 in the molar ratio of 0.85 : 0.15, followed by acid-hydrolysis. Polymer 3 showed excellent transparency above 300nm in the UV-visible spectrum. The photosensitive polymer containing polymer 3 (72wt%), MBHP (18wt%), and DIAS (10wt%) showed a sensitivity (D0.5) of 7.9M/cm2 and a contrast (r0.5) of 9.3 when it was exposed 365nm light and postbaked at 125°C for 3min, followed by developing a 2.38wt% aqueous tetramethylammonium hydroxide TMAH solution at 25°C.