coding:utf-8

class Animal(object):
def init(self,name):
self.name = name
def walk(self):
print(self.name+' is walking')
class Anima(Animal):
def init(self,name):
self.name = name
def ps(self):
print(self.name+' is ps')

class Dog(Anima):

def bark(self):
    print(self.name+' is bark')

dog = Dog('dog')
dog.walk()
dog.bark()
dog.ps()

你的__init__方法写成了init，不合规范

你的子类没有调用父类的__init__方法，并且dog类没有def init