This paper investigates the friction and friction heat of the micronscale iron under the influences such as the velocity of the slider and temperature of the substrate by using the smoothed particle hydrodynamics simulations. It is found that in the velocity range of 10–100 m/s, the sliding velocity–friction coefficient relationship well complies with the fitted exponent or hyperbolic tangent function, and the friction coefficient approaches a stable value of 0.3 at around the velocity of 50 m/s after a rapidly increasing situation. The steady friction coefficient maintains over the temperature range of 200–400 K. The friction heat is detailed analyzed versus the sliding time. The sliding time–system temperature relationship is well fitted by the sigmoidal functions, except the interfacial particle layers. The layer causing friction shows the highest steady temperature and largest temperature rise. The increment between the initial temperatures of the slider and the substrate strongly results in the temperature rise while it does not affect the configuration of the sliding time–system temperature curves.