diff --git a/recommendation/recommendation-FFM-Demo/FFM_model.py b/recommendation/recommendation-FFM-Demo/FFM_model.py
index 0a0d0a6e..de83326a 100644
--- a/recommendation/recommendation-FFM-Demo/FFM_model.py
+++ b/recommendation/recommendation-FFM-Demo/FFM_model.py
@@ -112,8 +112,8 @@ def gen_data():
             tf.reduce_sum(tf.multiply(lambda_v, tf.pow(thirdWeight, 2)),axis=[1,2])
         )
     )
-
-    loss = tf.log(1 + tf.exp(input_y * y_)) + l2_norm
+    #for single instance per round，`tf.reduce_sum` can be ignored
+    loss = tf.log(1 + tf.exp(-input_y * y_)) + l2_norm
 
     train_step = tf.train.GradientDescentOptimizer(learning_rate=lr).minimize(loss)