It is well established that solar X-rays and extreme ultraviolet(EUV) radiations are mainly responsible for the formation of the middle-and low-latitude ionosphere via ionizing the upper atmosphere.These solar radiations are known to have different period variations(e.G.，Lundstedt et al.，2005)，especially the well-known solar cycle variations.As a result，many parameters of the ionosphere are subjected to solar activity effects as well as diurnal，seasonal，and spatial variations.Observations indicate that，parameters of the Earths ionosphere，such as the critical frequency (foF2)，the peak electron density of the F region(NmF2)，and the total electron content(TEC)，are strongly controlled by solar activity in a rather complicated way(e.G.，Adler et al.，1997；Balan et al.，1994，1996；Bilitza，2000；Huang and Cheng，1995；Kane，1992，2003；Kouris et al.，1998；Kuznetsov et al.，1998；Lei et al.，2005；Liu et al.，2003；Liu et al.，2004a，2004b，2006；Mikhailov and Mikhailov，1995a，b；Pancheva and Mukhtarov，1998；Rao and Rao，1969；Richards，2001；Richards et al.，1994b；Rishbeth，1993；Sethi et al.，2002；Sojka et al.，2006；Su et al.，1999).Considerable progress has been made in understanding the solar activity effects of the ionospheric parameters.In this brief report，we will focus on four points：(1)Solar proxies；(2)solar activity effects of ionospheric parameters，such as NmF2，hmF2 and TEC；(3)solar activity effects of topside plasma density and compositions；and (4) the ionosphere under extreme conditions.