The invention provides a microalloy combined core-spun 
yarn for the 
high intensity structural steel, comprising a 
carbon steel sheath and a 
powder inner core, wherein, the element components and the 
mass percentage inside the 
powder inner core are as follows: C ranges from 0.6 to 0.9, Ca ranges from 18 to 22, Si ranges from 45 to 50, Mg ranges from 0.3 to 0.6, Ba ranges from 0.5 to 1.5, rare 
metal ranges from 0.2 to 0.5, B ranges from 0.3 to 0.7, Zr ranges from 1.6 to 2.0, Ti ranges from 1.2 to 1.8, Mn ranges from 0.08 to 0.12, P ranges from 0.2 to 0.6, S ranges from 0.2 to 0.6, and Fe occupies the rest percent. The microalloy combined core-spun 
yarn improves the steel intensity obviously, ensures that the lengthwise and transverse 
impact properties of the steel can be isotropic, thins 
crystal grains to ensure that the strip 
foreign substance is spherified and is distributed inside a base body, eliminates an aliquation line inside a continuously cast bloom, improves the performance, and is suitable for the outdoor refinement of the structural steel with the 
high intensity more than or equal to 800 MPa and the high impelling strength CV 
ranging from 250 to 300 J at 20 DEG C below zero.