The carrier and spin dynamics in solution-processed PbI_2film on quart z substrate have been systematically studied by transient reflectance (TR) spectroscopy and femto second resolved Kerr rotation spectroscopy. The results show that TR spectroscopy includes one b and of photo-induced bleach (PB) centered at 502nm and two bands of photo-induced ab sorption (PIA) at 487and 522nm,which are interpreted by band filling effect and band gap renorm alization effect.The Kerr magneto-optical signals excited by left-handed and right-handed circular ly polarized light are completely opposite in sign and almost equal in size.With the increase of pump fluence,the Kerr rotation angle and ellipticity increase linearly at first,then slowly,finally reach maximum value,~10degree and 0.12per micro,respectively.At the same time,the spin relaxation l ife decreases a minimum value ~1.6ps.According to our experimental data,the spin relaxation m echanism in PbI_2thin films is attributed to the Elliott-Yafet process owing to the strong spin -orbit coupling caused by the heavy atom lead.In addition,we find that Kerr effect has a large signal ar ound the band gap, which suggests that the spintronic devices based on PbI_2have high sensitivity around the band gap. These experimental results obtained in this paper are of great significance for exploring the potential applications of PbI_2thin films in spintronic devices.