A measuring method for total active sulfur in petroleum fraction is to reduce bisulfide and element sulphur in petroleum fractions with zinc powder and then to use solution mixture of ammonia water and alcohol as a titration agent, glass electrode as an reference electrode, silver-silver sulfide electrode as an indicating electrode and at last to use alcohol solution of silver nitrade to make theelectride potential titration. Advantages is single time and accurated measuring total active sulphur.