得到站点中所有的Content Type

SPContentTypeId id =newSPContentTypeId(BaseContentTypeId);
IList<SPContentType>ContentTypes= web.ContentTypes.Cast<SPContentType>().Where(c => c.Id.IsChildOf(id)).ToList();

using(SPSite site =newSPSite(SPContext.Current.Site.Url))
{
  using(SPWeb web = site.OpenWeb())
   {
     SPContentTypeCollection allContentTypes = web.ContentTypes;
                SPContentTypeCollection docContentTypes =null;
                foreach(SPContentType objContentType in allContentTypes)
                {
                    if(objContentType.Parent.Name=="Document")
                    {
                        docContentTypes.Add(objContentType);
                    }
                }
                // docContentTypes contains all content types derived from content type "Document". You can implement additional checks and add this into a drop down list.
    }
}

可以通过名字去取：

SPContentType spct = web.AvailableContentTypes["ContentTypeName"];