似乎是connection自己断了解决的办法是在创建conn的时候添加下面这句

conn.keep_this = conn_session

完整代码

def create_a_conn(ip_addr, port, username, password):‘‘‘creat a conn to router using paramiko.SSHClient()‘‘‘conn_session = paramiko.SSHClient()conn_session.load_system_host_keys()conn_session.connect(ip_addr, port, username, password, look_for_keys = False, allow_agent = False)conn = conn_session.invoke_shell()# to keep the session go onconn.keep_this = conn_sessiontime.sleep(1)conn.send("terminal length 0\n")time.sleep(1)if conn.recv_ready():conn.recv(65535)return conn