Finally found a solution. really hard. spend a lot of time on this issue.
The discussion is at here:
https://github.com/clojure-emacs/clojure-mode/pull/465 Here is my final
source code. paste here as a copy. Hope can help someone want same thing.

;; auto start CIDER REPL session in a complete Leiningen project
environment for Org-mode Babel by jack-in.
(add-to-list 'org-babel-default-header-args:clojure
             '(:session . "*cider-repl ob-clojure*"))
(progn
  (find-file (expand-file-name
"~/.emacs.d/Org-mode/ob-clojure/src/ob_clojure/core.clj"))
  (cider-jack-in))

(defun ob-clojure-cider-do-not-find-ns ()
  "Fix the issue that `cider-current-ns' try to invoke
`clojure-find-ns' to extract ns from buffer."
  (with-current-buffer "*cider-repl ob-clojure*"
    (defvar ob-clojure-cider-repl-ns cider-buffer-ns)
    (setq-local cider-buffer-ns ob-clojuure-cider-repl-ns)))
(add-hook 'org-mode-hook #'ob-clojure-cider-do-not-find-ns)



[stardiviner]           <Hack this world!>      GPG key ID: 47C32433
IRC(freeenode): stardiviner                     Twitter:  @numbchild
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Blog: http://stardiviner.github.io/

On Tue, Dec 19, 2017 at 5:54 PM, stardiviner <numbchild@gmail.com> wrote:

> I got new update on this issue.
>
> I think it is caused by `(clojure-find-ns)`.
> Here is my found:
>
> I created a simple clojure project for used by all org-babel-clojure src
> blocks.
> ```elisp
> (progn
>   (find-file (expand-file-name "~/.emacs.d/Org-mode/ob-clojur
> e/src/ob_clojure/core.clj"))
>   (cider-jack-in))
> ```
>
> I edebug the `org-babel-execute:clojure` process,
>
> `org-babel-execute:clojure' has a step: ~(clojure-find-ns)~ .
> This is from ~clojure-mode~. It will find current clojure buffer possible
> clojure namespace (even in org-mode). When I the following example org-mode
> buffer, it will return "namespace-not-found" error in nrepl response dict.
> Then src blcok has no error, not results.
>
> ```org
> #+BEGIN_SRC clojure :session
> (in-ns 'user-kk)
> or
> (ns user-kk)
> #+END_SRC
>
> #+BEGIN_SRC clojure :results output
> (print "hi")
> #+END_SRC
> ```
>
> Here is a part of function `clojure-find-ns`:
>
>       #+begin_src emacs-lisp
>       (when (or (re-search-backward clojure-namespace-name-regex nil t)
>                 ;; Or any form at all.
>                 (and (goto-char (point-min))
>                      (re-search-forward clojure-namespace-name-regex nil
> t)))
>         (match-string-no-properties 4))
>       #+end_src
>
> So I created an PR to disable find namespace in Org-mode buffer:
> https://github.com/clojure-emacs/clojure-mode/pull/465
>