写在前面

import tensorflow as tf
import numpy as np

t1 = [[1,2,3], [4,5,6]]
t2 = [[7,8,9], [3,4,5]]

t3 = tf.concat([t1, t2], 0)
t4 = tf.concat([t1, t2], 1)

sess = tf.InteractiveSession()
sess.run(tf.global_variables_initializer())

print sess.run(t3)
print sess.run(t4)

[[1 2 3]
 [4 5 6]
 [7 8 9]
 [3 4 5]]
[[1 2 3 7 8 9]
 [4 5 6 3 4 5]]