使用Python的turtle库绘制国旗的程序如下：
```python
import turtle
设置国旗的尺寸和颜色
width = 600
height = 400
red = "FF0000"
yellow = "FFFF00"
创建turtle对象并设置绘图窗口的大小
turtle.setup(width, height)
绘制国旗矩形背景
turtle.penup()
turtle.goto(-width/2, height/2)
turtle.pendown()
turtle.color(red)
turtle.begin_fill()
turtle.forward(width)
turtle.right(90)
turtle.forward(height)
turtle.right(90)
turtle.forward(width)
turtle.right(90)
turtle.forward(height)
turtle.right(90)
turtle.end_fill()
绘制国旗上的大五角星
star_size = 0.4
star_x = -width / 2 + 50
star_y = height / 2 - 50
star_length = height / 5 * star_size
turtle.penup()
turtle.goto(star_x, star_y)
turtle.pendown()
turtle.color(yellow)
turtle.begin_fill()
turtle.down()
for i in range(5):
turtle.forward(star_length)
turtle.right(144)
turtle.forward(star_length)
turtle.left(72)
turtle.end_fill()
隐藏turtle
turtle.hideturtle()
结束绘制
turtle.done()
```
这个程序首先设置了国旗的尺寸和颜色，然后创建了一个turtle对象并设置了绘图窗口的大小。接着，它绘制了国旗的矩形背景，并在中央绘制了一个大五角星。最后，它隐藏了turtle并结束了绘制。
