The invention relates to a catalytic 
system for preparation of wide-distribution 
polyolefin, and application of the catalytic 
system. The catalytic 
system comprises a 
solid catalyst component (A), a cocatalyst (B) and a first external 
electron donor (ED1), wherein the component (A) is a 
magnesium halide loaded Ti 
solid component and contains a composite internal 
electron donor (ID); the first external 
electron donor (ED1) is selected from one or more of compounds as shown in a general formula (1), (the formula is as shown in the description); and the R1 is selected from C1-C6 
alkyl, C3-C8 naphthenic base, C6-C14 
aryl or C6-C14 ceteroary, R2 is selected the formulas as shown in the description, and R3 is selected from OR1, R2, C1-C6 
alkyl and C3-C8 naphthenic base. When being applied to 
olefin polymerization, the catalytic system has various advantages: catalytic activity and 
hydrogen sensitivity are high; and the 
polymerization product is high in isotactic index, wide in molecular 
weight distribution and high in weight-average molecular weight.