在C#中使用Intersect方法對自定義對象列表進行交集操作，需要重寫自定義對象的Equals和GetHashCode方法，以確保比較兩個對象是否相等的準確性。

假設有一個自定義對象Person，包含屬性Id和Name，示例代碼如下：

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }

    public override bool Equals(object obj)
    {
        if (obj == null || GetType() != obj.GetType())
        {
            return false;
        }

        Person other = (Person)obj;
        return Id == other.Id && Name == other.Name;
    }

    public override int GetHashCode()
    {
        return Id.GetHashCode() ^ Name.GetHashCode();
    }
}

然后創建兩個Person對象列表，使用Intersect方法找到它們的交集：

List<Person> list1 = new List<Person>
{
    new Person { Id = 1, Name = "Alice" },
    new Person { Id = 2, Name = "Bob" },
    new Person { Id = 3, Name = "Charlie" }
};

List<Person> list2 = new List<Person>
{
    new Person { Id = 2, Name = "Bob" },
    new Person { Id = 3, Name = "Charlie" },
    new Person { Id = 4, Name = "David" }
};

var intersectList = list1.Intersect(list2).ToList();

foreach (var person in intersectList)
{
    Console.WriteLine(person.Id + " " + person.Name);
}

以上代碼將輸出：

2 Bob
3 Charlie