Abstract: This paper discusses the necessity for subdivision of A type suites into A1 and A2 subtypes and the judging criteria to distinguish them，based on new data obtained in study on A type suites in north Guangdong province and the data published in Chinese and overseas literature． The A type suites can be divided into two subtypes and three groups(A1 subtype：AS group；A2 subtype：ALAG group and AAG group)．The A1 subtype(AS group)is usually SiO2-undersaturated，metaluminous，and peralkaline-alkaline rocks，which include feldspathide syenites, a1kaline syenites and phonolites ．They are essentially characterized by existence of more or lass amount of feldspathide minerals such as Sodalite，nepheline，leucite etc．The A2 subtype is usually Si02-oversaturated，alkaline-subalkaline granitic rocks，which include the peraluminous，subalka1ine A type granites (ALAG group)，and the metaluminous，alkaline A type granites (AAG group)．Distinguishable from the ALAG group，the AAG group generally contains more or less amount of Ca-Na-or Na-pyroxenes and amphiboles ．Geochemically，the A1 subtype has relatively lower Si02(54.13％ ～61.29％)，higher ALK (12.65％ ～ 13.50％)，NK／A (0.85～1.03)，chlorine(50×10-6 ～9600×10-6)，R2(623，average，the same below)，Nb/Ta (15.69)，Zr／Hf(36.17)，Eu/Eu* (0.60)，LREE/HREE (15.18) and zircon．saturation temperature(833℃ )，and relatively lower R1(-263)，10^4 Ga/A1(2.4)，Y/Nb(0.34，similar to OIB source materials)and relatively lower fluorine(50×10-6～3523×10-6)．In contrast to A1 subtype，the AAG group of A2 subtype has relatively higher SiO2(71.93％-76.28％)，lower ALK(7.81％ ～9.80％)，chlorine(26×10-6～500×10I6)，R2 (318，in average，the same below)，Nb／Ta(13.09)，Eu／Eu* (0.29)and LREE/HREE (7.57)，and higher R1(2295)，10^4 Ga/A1 (3.93)，Y (1.64，similar to IAB source materials)，higher fluorine(6OO×10-6 ～1900×10-6)and zircon-saturation temperature(883℃ )．The ALAG group of A2 subtype is similar in geochemical properties to the AAG group，but is peraluminous．Using a series of diagrams of R1-R2，Y/Nb-Yb/Ta, Nb-Y - Ce and Nb/Ta-Nb，the A type suites can be readily distinguished into A1 and A2 subtype ．Based on the Nd，Sr isotopic data and using the mixing model of depleted mantle endmember and bulk crust endmember, it is calculated that the source materials for most A2 subtype granites of seven rock bodies are dominated by depleted mantle endmember component(68％ ～78％)．The mixing model of depleted mantle endmember and enriched mantle endmember shows that the source material components for A1 type rock suites are composed of EM4DM96-EM17DM83，and the enriched mantle endmember comprises only a minor proportion．