你在增加 line_num 对于空行和非空行。你应该是递增的 empty_lines 什么时候 len(line) == 0 .
自从 line_num 应该计算所有行，在任何条件之外递增。

import sys

def read():
    file_name = input("Name of the file to be read: ")
    try:
        with open(file_name, 'r') as file:
            lst = []
            line_num = 0
            accept_line = 0
            reject_line = 0
            empty_line = 0
            for line in file:
                line_num += 1
                line = line.strip() 
                if (len(line) == 0):
                    empty_line += 1
                elif (line.isalpha()):
                    accept_line += 1
                    lst.append(line)
                else:
                    reject_line += 1

        print("Read", line_num, "lines")
        print("Rejected", reject_lines, "lines")
        print("Empty", empty_line, "lines")
    except FileNotFoundError:
        print("open", file_name, "failure.")
        sys.exit(0)
    return lst, accept_line

什么时候 len(line.strip()) == 0 你必须增加 empty_line 也
你可以用这个

import sys
    def read():
        file_name = input("Name of the file to be read: ")
        try:
            file = open(file_name, 'r')
            lst = []
            line_num = 0
            accept_line = 0
            reject_line = 0
            empty_line = 0
            for line in file:
                line = line.strip() 
                if (len(line.strip()) == 0):
                    line_num += 1
                    empty_line += 1
                if (line == "\n"):
                    line_num += 1
                if (len(line) != 0):
                    line_num += 1
                if (line.isalpha()):
                    accept_line += 1
                    lst.append(line)
                else:
                    reject_line += 1
            print("Read {} lines".format(line_num))
            print("Rejected {} lines".format(reject_line))
        except FileNotFoundError:
            print("open", file_name, "failure.")
            sys.exit(0)
        file.close()
        return lst, accept_line