Total mesorectal resection (TME) is the standard surgical method for locally advanced rectal cancer, which significantly reduces the local recurrence rate. However, the incidence of urogenital dysfunction is higher. Studies found that Denonvilliers' Fascia contains autonomic nerves that may regulate urogenital function, while traditional TME surgery resects part of it. Recent Studies found that complete preservation of Denonvilliers' Fascia could improve urogenital in selected patients with rectal cancer. Locally advanced patient (T3-4 and/or N+, M0) accounts for a high proportion of mid-low rectal cancer. However, whether these patients can benefit from it has not fully been demonstrated. This project conducts a multi-center randomized controlled study to evaluate the effects of complete preservation and partial preservation of Denonvilliers' Fascia on postoperative urogenital function of locally advanced non-anterior mid-low rectal cancer.

Inclusion Criteria:

1. Pathological diagnosis of rectal adenocarcinoma;
2. Preoperative staging cT3-4 and or N+，M0 rectal cancer (AJCC- 7th);
3. Non-anterior wall, mid-low rectal cancer from 0 to 12 cm from the anal verge measured by rigid proctoscope;
4. R0 surgical results is expected by transabdominal or transanal TME/TSME;
5. 18 < age (years) < 71, informed consent;
6. Normal erection function (IIEF-5>21), ejaculation function grading as I level, FSFI > 26, normal urinary function (Bladder residual urine<100ml);
7. Preoperative ASA grade I ~ III, no serious systemic disease;

Exclusion Criteria:

1. Preoperatively confirmed peritoneum or distant metastasis;
2. Intraoperative confirmed invasion of surrounding tissues or organs, cannot be R0 resected;
3. With other malignant diseases;
4. With acute ileus, perforation or hemorrhage,need emergency surgery;
5. Critical organs dysfunction, unable to tolerate laparoscopic surgery;
6. With severe mental illness, cannot be evaluated;