当我按下按键时，为什么我的精灵不在pygame中移动？

您需要在属性中存储的位置上绘制Spriterect：

screen.blit(player.surf, (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))

screen.blit(player.surf, player.rect)

pygame.Surface.get_rect.get_rect()返回具有Surface对象大小的矩形，但是由于Surface对象没有位置，因此它返回始终以（0，0）开始的矩形。
Surface放置在blit显示器上的某个位置。

您必须通过关键字参数来设置矩形的位置，例如：

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
class Player(pygame.sprite.Sprite):
        def __init__(self):
            super(Player, self).__init__()
            self.surf = pygame.Surface((75,25))
            self.surf.fill((255, 255,255))
 
           self.rect = self.surf.get_rect(center = (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))

        # [...]

使用pygame.sprite.Group。pygame.sprite.Group.update()和pygame.sprite.Group.draw()是由提供的方法pygame.sprite.Group。
前者将委派给所update包含pygame.sprite.Sprites的方法-您必须实现该方法。

pygame.sprite.Group.update()

在组中的所有Sprite上调用update（）方法。

稍后使用包含的的image和rect属性pygame.sprite.Sprite绘制对象-您必须确保pygame.sprite.Sprites具有必需的属性

pygame.sprite.Group.draw()

将包含的Sprite绘制到Surface参数。这将Sprite.image属性用于源曲面，将Sprite.rect用于位置。

class Player(pygame.sprite.Sprite):
        def __init__(self):
            super(Player, self).__init__()
            self.image = pygame.Surface((75,25))
            self.image.fill((255, 255,255))
            self.rect = self.image.get_rect(center = (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))

player = Player()

all_sprites = pygame.sprite.Group()
all_sprites.add(player)

while running:
    # [...]

    #gets the keys that were just pressed
    pressed_keys = pygame.key.get_pressed()
    #updates location based on keys
    all_sprites.update(pressed_keys)

    # Give the surface a color to separate it from the Background
    screen.fill((0, 0, 0))
    all_sprites.draw(screen)
    pygame.display.flip()

完整的例子：

import pygame
#import pygame locals
from pygame.locals import(
    K_UP,
    K_DOWN,
    K_LEFT,
    K_RIGHT,
    K_ESCAPE,
    KEYDOWN,
    QUIT,
)

#constants for screen width/height
SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
class Player(pygame.sprite.Sprite):
        def __init__(self):
            super(Player, self).__init__()
            self.image = pygame.Surface((75,25))
            self.image.fill((255, 255,255))
            self.rect = self.image.get_rect(center = (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))

           #Moves sprite based on keypresses
        def update(self, pressed_keys):
            if pressed_keys[K_UP]:
                self.rect.move_ip(0, -5)
            if pressed_keys[K_DOWN]:
                self.rect.move_ip(0,5)
            if pressed_keys[K_LEFT]:
                self.rect.move_ip(-5,0)
            if pressed_keys[K_RIGHT]:
                self.rect.move_ip(5, 0)

pygame.init()
#create screen
screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))

# Instantiate player
player = Player()

all_sprites = pygame.sprite.Group()
all_sprites.add(player)

#keep the game running!
running = True

#loop time!
while running:
    #look at all the events
    for event in pygame.event.get():
        #did the user hit a key?
        if event.type == KEYDOWN:
            #Was it escape?  uh oh we gotta stop
            if event.key == K_ESCAPE:
                running = False

        elif event.type ==QUIT:
            running = False

    #gets the keys that were just pressed
    pressed_keys = pygame.key.get_pressed()
    #updates location based on keys
    all_sprites.update(pressed_keys)

    # Give the surface a color to separate it from the Background
    screen.fill((0, 0, 0))
    all_sprites.draw(screen)
    pygame.display.flip()