If the first-filed invention has not been published, you can withdraw it and reapply for a utility model; if it has been published but less than 12 months from the filing date, you can apply for a utility model by claiming domestic priority. New type; if it has been disclosed and it is more than 12 months from the application date of the invention patent, you can also apply for a utility model and obtain authorization. However, if the content of the utility model you apply for protection has been disclosed by the above-mentioned invention, you can still apply for a utility model. And it may be authorized (not necessarily, currently the State Intellectual Property Office will reject obviously abnormal applications), but if you really want to protect it, it is of little significance and it is very easy to be invalidated. Of course, you can apply after improving the content of your invention.