A solid titanium complex catalyst for polymerization and copolymerization of ethylene is prepared by the process comprising: (1) preparing a magnesium solution by reacting a halogenated magnesium compound with an alcohol; (2) reacting the magnesium solution with an ester compound having at least one hydroxyl group and a boron compound having at least one alkoxy group to produce a magnesium composition; and (3) producing a solid titanium catalyst through recrystallization by reacting the magnesium composition solution with a mixture of a titanium compound and a haloalkane compound; and optionally reacting the solid titanium catalyst with an additional titanium compound. The solid titanium complex catalyst for polymerization and copolymerization of ethylene according to present invention exhibits high catalytic activity and can be advantageously used in the polymerization and copolymerization of ethylene to produce polymers of high bulk density, narrow particle size distribution and small amount of fine particles.