The invention relates to a method for preparing tetrahydrofuran by 1, 4-butanediol through cyclodehydration; a catalyst for cyclodehydration reaction is a strong acidic ion exchange resin and the reaction temperature is 50 to 150 DEG C; as the strong acidic ion exchange resin catalyst is adopted, the reaction can be carried out under lower temperature and pressure, which greatly improves the processing capacity of the 1, 4-butanediol simultaneously when maintaining higher conversion rate and selectivity; furthermore, the catalyst has no causticity; special devices are not needed in the reaction process; and the temperature and pressure needed by the reaction are lower, thereby reducing the energy consumption and the manufacture cost to a large extent.