how to pass the multiple parameters to the system.threading.timer()

You need the visibility of the parameters not for the timer itself, but just for the timer callback. A timer callback can be an instance method of some class. As all instance method, it can access to the (hidden) reference "this" which is the reference to some instance of the class where you callback is declared. As "this" references the instance of whole class, you can put all your parameters in this class, so the callback method will directly access them.

Let's illustrate it on a simple example.

using System.Threading;

//...

//I don't know what is this:
internal class DatabaseTransfer {/*...*/}
   
internal class TimedProcessor {
    TimedProcessor() {
        Timer = new Timer(TimerCallback);
        //...
    } //TimedProcessor
    System.Threading.Timer Timer;
    void TimerCallback(object state) { //important: not static
        if (this.Row != 0) {/*...*/} //just for example
        this.DatabaseTransfer.//... whatever...
    } //TimerCallback
    //...
    DatabaseTransfer DatabaseTransfer;
    int Row, DueTime, Interval;
    //whatever else
} //class TimedProcessor

I don't know what you need to do int the timer callback TimeCallback. method. I just illustrated, that it can access all instance or static members of the same instance of TimedProcessor. Note, that I put an instance of the Timer in the same class only for simplicity. This class can be&hellop; well, anything. The Timer instance can be in any other class; the only important point here is that TimerCallback is the instance method and this method is put in the same class where your "parameters" are.

The qualification prefix "this." in this particular example is redundant; and you can omit it as it is implied. I put it in the code just to make my explanations more clear.

Problem solved.

I would also bring to your attention that in most cases timers should not be used, as an extra thread can do the same job in much more robust and safe way and easier to program. Please see my past answer where I explain it:
Timer Threading in C#[^].

—SA

You object row can contain anything.
So you can actually pass another object instance of a class with lots of properties in it - thus effectively passing multiple parameters.

Sample here[^].