We studied solar coronal X-ray jets by MHD numerical simulations with heat conduction effects based on a magnetic reconnection model. Key physical processes are included, such as the emergence of magnetic flux from the convection zone, magnetic reconnection with the coronal magnetic fields, heat conduction to the chromo-sphere, and chromospheric evaporation. Radiation, however, has been neglected. High-density evaporation jets were successfully reproduced in the simulations. The mass of the evaporation jets M is described as M ¼ 6:8 ; 10 12 g(B=10 G) 15=7 (T cor =10 6 K) 5=14 (L=5000 km) 12=7 (t=400 s), where B is the strength of magnetic fields, T cor is the coronal temperature, L is the loop height, and t is the duration of ejection, respectively. We also derived a theo-retical model of the Mach number of the reconnection jets as a function of ambient coronal variables. Numerical simulations also show that two different types of jets (evaporation jets and low-density jets) exist simultaneously around the emerging flux region, and the energy of evaporation jets is somewhat larger than that of the low-density jets.