Although a variety of processing routes were developed to in-situ manipulate microstructure for fabri-cating high-performance Ti-6Al-4V alloy by directed energy deposition (DED),the in-situ microstructural control ability has been limited and lead to a narrowed mechanical property control range.This work proved the microstructural correlation betweenβ-grains and α-laths resulting from the unique thermal characteristics of DED for the first time and solved such a dilemma through synchronous induction heat-ing assisted laser deposition (SILD) technology.The results confirmed that the laser energy and inductive energy have a different effect on the solidification and solid phase transformation conditions.By adjust-ing the laser-induction parameters,the microstructural correlation can be tuned;the β-grains and α-laths can be controlled relatively separately,thereby significantly enhancing the ductility of as-deposited sam-ple (elongation from 14.2％ to 20.1％).Furthermore,the mechanical properties of the tuned microstructures are even comparable to that of DED Ti-6Al-4V with post heat treatment,which indicates that the poten-tial of SILD to be a one-step manufacturing process to fabricate high performance components without post heat treatment.Furthermore,the tensile testing results of the tuned microstructures indicate that α-lath size is more influential on the mechanical properties than the β-grain size due to its stronger hin-dering effect on the slipping of dislocations.This work promotes the understanding of the microstructural formation mechanism in DED titanium alloy and proves that the combination of synchronous induction and laser can expand the ability to control the microstructure and properties of multi-layer deposition.