The invention relates to biphenyl molecular glass and a preparation method thereof, namely preparation of 2, 2' 1 2 (3, 5-di-tert-butyl-di-carbonate)-4, 4'-1 2 (di-tert-butyl-di-carbonate) biphenyl compound A and 2, 2', 4, 4'-4 (3, 5-di-tert-butyl-di-carbonate) biphenyl compound B. The diazotization reaction is conducted on 2, 2' 1 2 (3, 5-di-tert-butyl-di-carbonate)-4, 4'-benzidine under the condition of NaNO2 / H2SO4, then the 2, 2' 1 2 (3, 5-di-tert-butyl-di-carbonate)-4, 4'-benzidine is heated and hydrolyzed under the acidity condition, demethylation is conducted under the condition of BBr3 to obtain 2, 2' 1 2 (3, 5-dyhydroxy-phenyl)-4, 4'-diphenol, and finally the 2, 2' 1 2 (3, 5-dyhydroxy-phenyl)-4, 4'-diphenol reacts with (t-Boc)2O to obtain the compound A. The 2, 2' 1 2 (3, 5-di-tert-butyl-di-carbonate)-4, 4'-benzidine is diazotized and then mixed with potassium iodide to obtain 2, 2' 1 2 (3, 5-di-tert-butyl-di-carbonate)-4, 4'-biphenyl-diiodine. The 2, 2' 1 2 (3, 5-di-tert-butyl-di-carbonate)-4, 4'-biphenyl-diiodine conducts Suzuki reaction with 3, 5-dimethoxy benzene boric acid under catalyst of Pd(Ph3)4 / K2CO3 to obtain 2, 2', 4, 4'-4(3, 5-dimethoxy) biphenyl. 2, 2', 4, 4'-4(3, 5-dyhydroxy-biphenyl) is obtained by demethylation through the BBr3 under low temperature and reacts with the (t-Boc)2O to obtain the compound B.