Based on the data of surface ozone in 1994.8~2001.12 over Waliguan the seasonal variation and the characteristics of surface ozone under different sky condition are analyzed. The results show that the surface ozone over clean area in Qinghai-Xizang plateau has significant seasonal variation，and it also keeps increasing with lowspeed，the concentration of O3 in spring is obviously higher than that in winter，the maximum is in the beginning of summer，the minimum is in January.Compared with Izanastation in Spain，the annual variation of two stations is very close，and also keeps increasing slowly.Under different sky condition，the variation of O3 in each season is alsodifferent；its variation in spring，summer and autumn is almost same.In spring and autumn，the O3 value in clear day is higher than that in rainy or cloudy day while it is insignificant in winter and summer，it illustrates that the clear day is favorable to the increasing of O3，but it is not so important.In rainy and snowy day，the variation of O3 ins pring，autumn and winter is not evident，but in summer，it is totally different from other seasons，its daily difference is the biggest among all seasons，this probably has some relationship with the washing of snow and rain，moreover the difference of snow and rain maybe important to the elimination of O3

The science objectives and principal results of the representative land surface process experiments(LSPE)  such as FIFE, LBA,HEIFE,IMGRASS,TIPEX and GAME一Tibet and so on ,which have been carried out since 1980's, are introduced.while .the weaknesses of LSPE are pointed out as well as what will be emphasized in the future.