Pycharm import within module broken

I am using Pycharm 2018.1 and Python 3.6

My project structure is

|  MyProject

|>>>>  __init__.py

|>>>>  train.py (Model)

|>>>> main.py

I defined a class named "Model" in "train.py". But when I tried to use the following codes import class Model in "main.py"

import train from Model

Pycharm gave me a statistic check error: Unresolved reference Model

However, I can run the program pretty well. Did I use import improperly or it is a bug?