测试代码：

import torch.nn as nn
class Model(nn.Module):
    def __init__(self):
        super(Model, self).__init__()
        self.conv1 = nn.Conv2d(10, 20, 4)
        self.conv2 = nn.Conv2d(20, 40, 4)

model = Model()

for m in model.modules():
    print(m)

结果：

Model(
  (conv1): Conv2d(10, 20, kernel_size=(4, 4), stride=(1, 1))
  (conv2): Conv2d(20, 40, kernel_size=(4, 4), stride=(1, 1))
)
Conv2d(10, 20, kernel_size=(4, 4), stride=(1, 1))
Conv2d(20, 40, kernel_size=(4, 4), stride=(1, 1))

结论：

　modules()返回一个包含 当前模型 所有模块的迭代器。