The total electron content (TEC) measured by GPS observations from the network of International GNSS Service (IGS) at the altitude of about 450 km in the 110°E longitude sector for more than a solar cycle term from January 2000 to December 2011 are used to study the northsouth asymmetry of the equatorial ionization anomaly (EIA). The parameters of the EIA crest obtained from the daytime TEC profiles for conditions of different solar activity have been used to study the solar cycle variations of EIA in the Southeast Asian region. Results show that the latitudinal position

occurrence time and strength of the EIA crest are found to be asymmetric about the magnetic equator and the conditions of solar activity have a remarkable effect on EIA crest and the northsouth asymmetry. The strength of EIA crest is obviously higher during periods of high solar activity

and the TEC average value of the EIA crest is obviously higher in the northern hemisphere during the daytime in all seasonal. The strength of the north crest is higher than that of the south crest in summer and autumn during low solar activity period

while smaller in winter.During high solar activity period

the occurrence time of the northern crest appears about 1 h later than that of the southern crest from June to August. And during low solar activity period

the occurrence time of the northern crest appears about 1 h earlier than that of southern crest in winter

while about 2 h later from May to September. With the solar activity increased gradually

the mean value of asymmetry index (Ia) increased obviously during winter solstice.