The invention relates to a coaxial cable with a compound inner conductor for use in a shallow sea bed and a manufacturing method thereof. The coaxial cable is characterized in that the inner conductor composed of a plurality of stranded soft round copper wires is wound outside a center conductor, a high pressure polyethylene insulating layer is extruded outside the compound inner conductor; an outer conductor is uniformly woven at the periphery of the high pressure polyethylene insulating layer; two layers of polyester film strips are lapped at the periphery of the outer conductor in opposite directions. and the periphery of the polyester film strip is successively coated with a first asphalt coating layer, a first dipped hemp rope lining layer, a second asphalt coating layer, a copper alloy wire armor layer, a third asphalt coating layer, a second dipped hemp rope lining layer, a fourth asphalt coating layer, a aluminum plated magnesium alloy steel wire armor layer, a fifth asphalt coating layer, a first dipped hemp wrapped strip layer, a sixth asphalt coating layer, a second dipped hemp wrapped strip layer, a seventh asphalt coating layer and a plastic film anti-sticking layer. The cable is stable in structure, good in anti-water-seepage, corrosion-resistant and anti-pulling performances, and stable in signal transmission when water impact occurs.