试试这样

//Get what uou need from the data
var result = context.Student
    .Where(x => x.Name) //Query the Db for what you need
    .Select(x => new
    {
        Birthday = x.Birthday.ToString("MM/dd/yyyy"), //Use format you need
        Name = x.Name
        //Add props you need from student
    }).ToList();

您可以在这里看到一些日期时间格式https://www.c-sharpcorner.com/blogs/date-and-time-format-in-c-sharp-programming1
或者，如果您想使用该模型，则可以在不影响数据库的情况下向其中添加ModifiedBirdday，如

public class Student
{
    //All student props

    [NotMapped]
    public string ModifiedBirthday => this.Birthday.Value.ToString("MM/dd/yyyy"); // Format you need

}