One transistor in my computer smps is blown, it looks burnt. Can I just replace it and use the smps? Is there any danger to my computer?

before anything else it is necessary to check the cause of the heating of the transistor

just remove power cord and  put off your computer and call electricain to check it out .

At first, check the cause of burning. generally it is caused by Excessive Voltage, Excessive current, Thermal Load.

Replacing the same transistor will not cause any other damages if they didn´t occur before. it will just blow up like the previous one if the cause is persistent.