In the present article, series of experiments were conducted to investigate turbulent explosion characteristics of stoichiometric syngas (with different hydrogen concentrations, 10%-90% in volume fraction) in a 28.73-L spherical turbulent premixed explosion system. The evolution of explosion pressure was recorded in different turbulent environment (with different turbulent intensity, 0.100-1.309m/s in root mean square value of velocity fluctuation). From the explosion pressure historic curves, the maximum pressure, lag duration, and explosion duration were obtained; the pressure rise rate and fast burn duration were derived; and deflagration index could be further calculated. The interaction effects of turbulent intensity and hydrogen addition on those explosion parameters were systematically analysed and discussed. Based on the results, an empirical formula about deflagration index of stoichiometric syngas was established.