Low-density hot dip galvanized steel, comprising a steel substrate (1) located at a core portion and a coating layer (3) located on the surface. An interface layer is disposed between the steel substrate (1) and the coating layer (3), the interface layer comprises an iron particle layer (4), iron particles dispersed on the steel substrate (1) and covering the steel substrate (1) are disposed in the iron particle layer (4), and the iron particles are covered by a first inhibition layer (5). The low-density hot dip galvanized steel contains element Al in a mass percentage of 3.0% to 7.0%. Correspondingly, the present invention also comprises a manufacturing method for the low-density hot dip galvanized steel. The low-density hot dip galvanized steel has a low density, a high strength and high galvanizability and coating layer adhesion.