This paper introduces the composition design， smelting， casting and rolling process of extra-thick plate 12Cr2Mo1VR（H） steel for hydrogenation reactor application， calculates the important phase change parameters such as heat diffusion rate， heat capacity and thermal conductivity of steel plate by JMatPro software， and analyzes the influence of heat treatment system on its organization， tempering embrittlement performance， high temperature persistence and creep performance. In the production process by adjusting Cr， Mo （Mn） and V contents， control the morphology and distribution of microstructure， promote the crystalline iron body core， using clean steel smelting technology to control harmful elements at a low level， reducing the tempering brittlement phenomenon produced by the polarization of grain boundaries of harmful elements， controlling the original grain size by using water cooling mold casting technology and control rolling technology. The performance detection results showed that the anti-tempering embrittlement temperature of 12Cr2Mo1VR（H） steel reached -51 ℃， after simulated thermal cycling， the difference of tensile properties of steel plate in X， Y and Z direction of steel plate was within 15 mpa， the impact energy of the surface layer， 1/4，1/2 and 3/4 of the thickness section was over 280 J， and there was no significant difference in the position trend. At the same time， the loading force at 540 ℃ temperature was 210 MPa without breaking for 1 010 h. The elastic elongation of high temperature creep was 0.147 5%， and the total plastic elongation was 1.454 5%， respectively