The invention provides a catalyst component and catalyst for vinyl polymerization, and preparation methods and application thereof. The preparation method for the catalyst component comprises the following steps: (1) subjecting a magnesium compound, an oxygen-containing titanium compound and an alcohol compound to contact and reaction so as to form a transparent solution of a magnesium-titanium complex; (2) contacting the transparent solution obtained in the step (1) with an ether compound for a reaction so as to obtain a homogeneous solution; (3) contacting the homogeneous solution obtained in the step (2) with a halogenation reagent for a reaction so as to obtain a suspension; and (4) subjecting the suspension obtained in the step (3) to curing, standing and settling, washing, and dryingso as to obtain the catalyst component. The method can realize formation of a totally-soluble uniform solution of the magnesium-titanium complex in a non-polar solvent at a low temperature, so energyconsumption is reduced; and the stacking density of powder is high, and the content of fine powder with sizes of 200 meshes or below in a polymer is low.