In the present article, the evolution of explosion pressure for 50%H-2-50%CO syngas-air mixtures with a wide range of equivalence ratio in various turbulent ambience had been experimentally studied in a 28.73-L fan-stirred explosion vessel. Equivalence ratio varied from 0.4 to 3.0, and the turbulent intensity varied from 0 to 1.309m/s. The results indicated that explosion indices (including maximum explosion pressure, explosion duration, and the maximum rate of pressure rise) were not monotonous to equivalence ratio, and the inflection equivalence ratio for different indices was different. The maximum explosion pressure was attained at the equivalence ratio of 1.2 for the reasons about maximum adiabatic flame temperature, the minimum explosion duration was attained at the equivalence ratio of 2.0 for the reasons about fastest laminar burning velocity, and the maximum rate of pressure rise was attained at the equivalence ratio of 1.6 for the competition effects of laminar burning velocity and adiabatic flame temperature. With the increase of turbulent intensity, the maximum explosion pressure and the maximum rate of pressure rise were raised albeit the growth tendencies were different for different ranges of equivalence ratio; the major reason to the growths was the heat transferred the wall during explosion had been reduced. Furthermore, with the increase of turbulent intensity, the value of deflagration index significantly rose even the values were higher than 30MPam/s for most cases in a weaker turbulent ambience; the results indicated that keeping the ambience quiescent is one better safety protection to syngas.