ScrollRect.verticalNormalizedPosition

public float verticalNormalizedPosition ;

Description

The vertical scroll position as a value between 0 and 1, with 0 being at the bottom.

using UnityEngine;
using System.Collections;
using UnityEngine.UI;  // Required when Using UI elements.

public class ExampleClass : MonoBehaviour
{
    public ScrollRect myScrollRect;
    public Scrollbar newScrollBar;

    public void Start()
    {
        //Change the current vertical scroll position.
        myScrollRect.verticalNormalizedPosition = 0.5f;
    }
}