diff --git a/opencompass/datasets/lawbench/evaluation_functions/ljp_imprison.py b/opencompass/datasets/lawbench/evaluation_functions/ljp_imprison.py
index 80b8ec2d..e051caf9 100644
--- a/opencompass/datasets/lawbench/evaluation_functions/ljp_imprison.py
+++ b/opencompass/datasets/lawbench/evaluation_functions/ljp_imprison.py
@@ -43,9 +43,12 @@ def compute_ljp_imprison(data_dict):
             score_list.append(abs(math.log(answer_digit + 1) - math.log(prediction_digit_month + 1)))
         else:
             score_list.append(math.log(216))
-
-    # compute the average of score_list (log distance)
-    log_distance = sum(score_list) / len(score_list)
-    # normalize the score to between 0 and 1
-    log_distance = (math.log(216) - log_distance)/math.log(216)
+    
+    if abstentions == len(score_list):
+        log_distance = 0
+    else:
+        # compute the average of score_list (log distance)
+        log_distance = sum(score_list) / len(score_list)
+        # normalize the score to between 0 and 1
+        log_distance = (math.log(216) - log_distance)/math.log(216)
     return {"score": log_distance, "abstention_rate": abstentions/len(data_dict)}