The present invention relates to a kind of non-cyclopentadiene catalyst for synthesizing syndiotactic polystyrene. The catalyst includes main catalyst comprising 2-hydroxy benzophenone titanium chloride, alkoxy compound and phenoxy or substituted phenoxy compound in the molar ratio of 2000 to 1-100 to 1; and co-catalyst alkyl alum inoxane. The catalyst has activity of 1E4-1E6 gPS/mol Ti. hr andmay be maintained for 2 hr without lowering; and may be produced through reaction at normal temperature in low cost. When it is used in producing syndiotactic polystyrene, the process is simple and easy to control and the molecular weight of the polymer is 150-300 kD.