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The influence of different extrusion ratios and extrusion temperatures(Holder temperature) on grain size and mechanical properties of AZ63M magnesium alloy were investigated and then the optimal aging treatment parameters and heat processing parameters of as-extruded AZ63M were studied. The extrusion experiments were undertaken with extrusion ratio of 9, 32, 41, 81 and extrusion temperature of 200℃, 250℃, 300℃. T5 and T6 heat treatment were used to develop mechanical properties and the heat processing map were depicted at temperature ranging from 300℃ to 450℃ with strain rate from 5×10-2s-1 to 5×10-4s-1. The results reveal that with the decreasing extrusion temperature from 300℃ to 200℃, the grain size decreased from 31μm to 14μm, the ultimate tensile strength and the elongation increased from 277MPa to 368MPa, 13.6% to 17.3% respectively. With the increasing extrusion ratio from 9 to 81, the average grain size refined from 24μm to 8μm, the UTS and the elongation increased from 277MPa to 376MPa was 376MPa, from 15.3% to 16.1% respectively. Subjected to T6 treatment, the UTS of as-extruded AZ63M increased by 18%, up to 390MPa and the elongation decreased by 6% compared with the as-extruded alloy (extrusion ratio: 32, extrusion temperature: 250℃) and the optimum heat processing parameters of as-extruded AZ63M were at temperature 400℃～450℃ and strain rate 5×10_-4 s_-1～1.5×10_-3s_-1.