import datetime
import threading

def func():
  print("haha")
  #如果需要循环调用，就要添加以下方法
  timer = threading.Timer(86400, func)
  timer.start()

# 获取现在时间
now_time = datetime.datetime.now()
# 获取明天时间
next_time = now_time + datetime.timedelta(days=+1)
next_year = next_time.date().year
next_month = next_time.date().month
next_day = next_time.date().day
# 获取明天3点时间
next_time = datetime.datetime.strptime(str(next_year)+"-"+str(next_month)+"-"+str(next_day)+" 03:00:00", "%Y-%m-%d %H:%M:%S")
# # 获取昨天时间
# last_time = now_time + datetime.timedelta(days=-1)

# 获取距离明天3点时间，单位为秒
timer_start_time = (next_time - now_time).total_seconds()
print(timer_start_time)
# 54186.75975


#定时器,参数为(多少时间后执行，单位为秒，执行的方法)
timer = threading.Timer(timer_start_time, func)
timer.start()