Highly ordered ethylene bridged periodic mesoporous organosilica (PMO) materials with ultra-large pore sizes up to 14.7 nm were successfully synthesized by using triblock copolymer F127 as a template and 1,3,5-trimethylbenzene (TMB) as a swelling agent. SAXS and TEM measurements show that PMO products have a face-centered cubic (space group of Fm3̄m) mesostructure. The influence of reaction temperature and acidity of the solution on the mesostructure of the PMO products were systematically studied. The pore size can be gradually expanded as the temperature decreases, and ordered PMOs can be obtained at a temperature even down to 5 °C with a relatively low acidity. As compared with mesoporous silica materials synthesized at identical conditions, our experimental results reveal that different hydrophobicity between precursors, bis(trimethoxysilyl)ethane and tetraethyl orthosilicate, may influence the swelling capacity of F127 micelles with TMB as well as the phase behavior of triblock copolymer F127, resulting in the different physicochemical properties of the final products.