食古不化

shígǔbùhuà
  1. to swallow ancient learning without digesting it (idiom)
  2. to be pedantic without having a mastery of one's subject

CEDICT

to rigidly adhere to old methods or styles without being flexible

Wiktionary

学了古代知识而不能充分理解、应用，如同吃了东西不能消化一样。用以比喻一味守旧而不知变通。

重編國語辭典

一味守旧而不知变通

維基詞典

Entry Composition

1 食 shí
  1. to eat
  2. food
  3. animal feed
  4. eclipse
2 古 gǔ
  1. ancient
  2. old
  3. paleo-
3 不化 bùhuà
  1. (literary) to not change; to be unchanged
  2. (literary) to not decay; to not spoil
  3. to not change; to be unchanged
  4. to not decay; to not spoil