Combing Gaia DR2 with LAMOST DR5, we spectroscopically identified 924 hot subdwarf stars, among which 32 stars exhibit strong double-lined composite spectra. We measured the effective temperature T_eff_, surface gravity logg, helium abundance y=nHe/nH, and radial velocities (RVs) of 892 non-composite spectra hot subdwarf stars by fitting LAMOST observations with TLUSTY/SYNSPEC non-LTE synthetic spectra. We outlined four different groups in the T_eff_--logg diagram with our helium abundance classification scheme and two nearly parallel sequences in the T_eff_--log(y) diagram. 3D Galactic space motions and orbits of 747 hot subdwarf stars with (G_BP_-G_RP_)0{=0 are from the double helium white dwarfs (HeWDs) merger, He-deficient hot subdwarf stars with -2.2<=log(y){<}-1 from the common envelope ejection, and He-deficient hot subdwarf stars with log(y){<}-2.2 from the stable Roche lobe overflow channels. The relative number of He-rich hot subdwarf stars with -1<=log(y)=0 in the halo is more than twice the prediction of Zhang+ (2017ApJ...835..242Z) by more than six times in the thin disk, which implies that the mergers of HeWDs with low-mass main-sequence stars may not be the main formation channel for He-rich hot subdwarf stars with -1<=log(y)<0, especially in younger environments.

Cone search capability for table J/ApJ/881/7/table2 (Atmospheric parameters and space positions for 892 non-composite spectra hot subdwarf stars selected from Gaia DR2 and LAMOST DR5)

Cone search capability for table J/ApJ/881/7/table3 (Orbital parameters, galactic velocities for 747 hot subdwarf stars selected from Gaia DR2 and LAMOST DR5)