Thank you for your reply.
My level didn’t allow me to post more than one image yesterday. There are some images during my training yesterday.(early stopping)

with eval()

without eval()
I’ve solved this problem today. It seemed that I’d used the same batch-norm layer for several times by mistake…hmmm I’m not sure in fact. Is there any difference between the codes?
now:

QQ截图20180927144108.jpg1091×245 26.8 KB

        norm_layer = get_norm_layer()
        net += [
            nn.Conv2d(ndf * nf_pre, ndf * nf_now, 4, 2, 1),
            norm_layer(ndf * nf_now),
            nn.LeakyReLU(0.2, True)
        ]

former:

QQ截图20180927144117.jpg1091×240 28.5 KB

        net += [
            nn.Conv2d(ndf * nf_pre, ndf * nf_now, 4, 2, 1),
            get_norm_layer(ndf * nf_now, norm),
            nn.LeakyReLU(0.2, True)
        ]