Thanks for the help everyone. I have got the answer.
var prop = typeof (TestA).GetProperties();
for (int i=0;i<prop.Count();i++)
{
var propertyInfo = prop[i];
if (propertyInfo.PropertyType.Namespace != "System")
{
if (propertyInfo.PropertyType.IsGenericType &&
propertyInfo.PropertyType.GetGenericTypeDefinition() == typeof (List<>))
{
Type itemType = propertyInfo.PropertyType.GetGenericArguments()[0];
var listObjectProperties = itemType.GetProperties();
prop = prop.Union(listObjectProperties).ToArray();
}
else
{
var childProp = propertyInfo.PropertyType.GetProperties();
prop = prop.Union(childProp).ToArray();
}
}
}