The invention relates to a loaded type polyolefin catalyst, a preparation method and an application, a main catalyst is composed of a carrier and a transition metal halide, a carrier is composed of a magnesium halide compound, a silicon halide compound, alcohol with carbon atoms number less than or equal to C5, and alcohol with carbon atoms number of C6-C20, wherein the mol ratio is 1: (0.1-20): (0.1-5): (0.01-10); the mol ratio of magnesium halide compound to transition metal halide is 1: (0.1-30); an organic alcohol ether compound is added during a preparation process of the main catalyst, wherein the mass ratio of the magnesium halide compound to the organic alcohol ether compound is 100: (0.1-20); and the mol ratio of the transition metal halide to cocatalyst in the main catalyst is 1:30-500. The catalyst has good particle form and uniform particle size distribution, the segmentation content of the obtained polymer through catalysis is low, the bulk density is high, and the loaded type polyolefin catalyst is suitable for an alkene slurry polymerization technology, gas phase polymerization technology or a combination polymerization technology.