Currently,　two-dimensional　(2D)　layered　transition　metal　chalcogenides　(TMCs),　especially　MoS2,　are　attracting　widespread　attention　in　the　field　of　water　electrolysis.　Unfortunately,　the　catalytic　activity　of　MoS2　is　limited　to　a　few　edge　sites　and　by　its　low　conductivity.　Herein,　MoS2/NiS　heterostructures　possessing　a　flower-like　morphology　were　constructed　via　an　accurate　thermal　treatment　process　to　realize　precise　interface　modification.　As　expected,　through　the　adjunction　of　a　certain　amount　of　polyvinylpyrrolidone,　NiS　grew　uniformly　on　the　surface　of　MoS2　nanosheets,　thereby　forming　a　large　number　of　visual　lattice　fringes　with　a　specific　interplanar　spacing,　which　promoted　a　higher　electron-transfer　efficiency.　The　better　electron-transfer　efficiency　resulted　in　a　better　hydrogen　evolution　reaction　performance,　providing　an　overpotential　of　158　mV　at　10　mA　cm(-1),　a　Tafel　slope　of　128.1　mV　dec(-1),　and　significantly　long-term　durability.　Moreover,　density　functional　theory　calculation　also　showed　that　the　precise　interface　modification　of　MoS2/NiS　heterostructure　exhibited　more　occupations　at　the　Fermi　level,　which　improved　the　electrical　conductivity.　Additionally,　the　MoS2/NiS　catalysts　achieved　a　moderately　lower　hydrogen　adsorption　energy　(Delta　G(H*)),　indicating　that　it　had　better　catalytic　hydrogen　evolution　performance.　This　work　can　be　extended　to　design　other　catalytic　materials　and　for　understanding　reactions　in　the　fields　of　energy　conversion　through　theoretical　calculations.