In　this　paper,　we　collect　and　process　free-field　strong　motion　recordings　from　70　earthquakes　for　4.2　＜　MW　＜　7.9　at　0　＜　Rrup　＜　300　km　between　2008　and　2018　in　the　active　tectonic　regions　of　southwest　China,　and　then　establish　a　dataset　containing　1324　average　horizontal　ground　motion　(ROTD50)　and　corresponding　metadata　such　as　parameters　of　the　earthquake　source,　distance,　and　site.　A　new　ground　motion　prediction　equation　(GMPE)　for　the　average　horizontal　component　of　peak　ground　acceleration　(PGA),　peak　ground　velocity　(PGV),　and　5%　damped　acceleration　response　spectra　at　periods　ranging　from　0.033　to　8.0　s　(SA　(T　=　0.033-8.0　s))　is　introduced.　This　GMPE　considers　multiple　influencing　factors　such　as　magnitude　and　distance　saturation　effect,　geometric　attenuation,　style-of-faulting,　hanging-wall　effect,　linear/nonlinear　site　response,　and　anelastic　attenuation.　The　residual　evaluation　and　median　ground　motion　are　presented.　The　predicted　ground　motions　using　the　new　GMPE　are　compared　with　predictions　from　the　GMPE　in　western　China　and　five　NGA-West2　GMPEs,　and　the　observed　ground　motions　of　strong　earthquakes　which　occurred　in　southwest　China.　The　results　show　that　the　proposed　GMPE　can　better　reflect　the　influence　of　the　earthquake　source　characteristic,　propagation　media,　site　effect　on　the　ground　motion　attenuation　characteristic　in　southwest　China,　and　works　well　versus　independent　strong　motion　data　of　earthquakes　in　southwest　China,　and　well　reflects　the　general　feature　of　ground　motions　for　the　Wenchuan　and　Lushan　earthquakes　that　is　rich　at　short-period　and　weak　at　long-period.　The　new　GMPE　shows　outstanding　performance　estimating　the　horizontal　ground　motion　of　the　earthquakes　in　southwest　China　for　MW　4.2-7.9　(related　to　style-of-faulting)　and　Rrup　=　10-200　km,　at　sites　with　VS30　=　140-1130　m/s.