I just replace the fuse in my magic chef mic model mcd1611st serie#dj12100526 could it be the door switch that's trip it

It's possible. The door latch pushes on a microswitch that powers the control board. Switch could be grounded or it could be an internal fault. Is it hung or counter top?

The only way to know is to use a meter to check it. Never guess when repairing an appliance of any type. You could also have a wire grounded or anything else. Start at the plug end and check from the prongs to ground and move through the appliance until you are not grounding something. Disconnect one thing at the time until you no longer get a ground and then check what you disconnected. Use the meter set to ohms, of course, with no power on. Here are a few manuals: https://dl.dropboxusercontent.com/u/...e%20Manual.pdf
https://dl.dropboxusercontent.com/u/...Electronic.pdf
https://dl.dropboxusercontent.com/u/...ning-ovens.pdf