please ignore this email. Resolved this issue by source ~/.zshrc. I sitll donot know why :)
$ vim ~/.zshrc
# mingmingding @ MINGMINDING-MB0 in ~/anaconda2/bin on git:master x [20:52:37]
$ source ~/.zshrc
(base) ➜ bin git:(master) ✗ pwd
/Users/mingmingding/anaconda2/bin
(base) ➜ bin git:(master) ✗ sudo conda list
# packages in environment at /Users/mingmingding/anaconda3:
#
# Name Version Build Channel
_ipyw_jlab_nb_ext_conf 0.1.0 py38_0
alabaster 0.7.12 py_0
anaconda 2020.07 py38_0
anaconda-client 1.7.2 py38_0
anaconda-navigator 1.9.12 py38_0
anaconda-project 0.8.4 py_0
applaunchservices 0.2.1 py_0
appnope 0.1.0 py38_1001
appscript 1.1.1 py38haf1e3a3_0
argh 0.26.2 py38_0
asn1crypto 1.3.0 py38_1
astroid 2.4.2 py38_0
astropy 4.0.1.post1 py38h01d97ff_1
atomicwrites 1.4.0 py_0
attrs 19.3.0 py_0
autopep8 1.5.3 py_0
babel 2.8.0 py_0
backcall 0.2.0 py_0
backports 1.0 py_2
backports.functools_lru_cache 1.6.1 py_0
backports.shutil_get_terminal_size 1.0.0 py38_2
backports.tempfile 1.0 py_1
backports.weakref 1.0.post1 py_1
beautifulsoup4 4.9.1 py38_0
bitarray 1.4.0 py38haf1e3a3_0
bkcharts 0.2 py38_0
blas 1.0 mkl
bleach 3.1.5 py_0
blosc 1.19.0 hab81aa3_0
bokeh 2.1.1 py38_0
boto 2.49.0 py38_0
bottleneck 1.3.2 py38hf1fa96c_1
brotlipy 0.7.0 py38haf1e3a3_1000
bzip2 1.0.8 h1de35cc_0
ca-certificates 2020.6.24 0
certifi 2020.6.20 py38_0
cffi 1.14.0 py38hc512035_1
chardet 3.0.4 py38_1003
click 7.1.2 py_0
cloudpickle 1.5.0 py_0
clyent 1.2.2 py38_1
colorama 0.4.3 py_0
conda 4.8.3 py38_0
conda-build 3.18.11 py38_0
conda-env 2.6.0 1
conda-package-handling 1.6.1 py38h1de35cc_0
conda-verify 3.4.2 py_1
contextlib2 0.6.0.post1 py_0
cryptography 2.9.2 py38ha12b0ac_0
curl 7.71.1 hb0a8c7a_1
cycler 0.10.0 py38_0
cython 0.29.21 py38hb1e8313_0
cytoolz 0.10.1 py38h1de35cc_0
dask 2.20.0 py_0
dask-core 2.20.0 py_0
dbus 1.13.16 h18a8e69_0
decorator 4.4.2 py_0
defusedxml 0.6.0 py_0
diff-match-patch 20200713 py_0
distributed 2.20.0 py38_0
docutils 0.16 py38_1
entrypoints 0.3 py38_0
et_xmlfile 1.0.1 py_1001
expat 2.2.9 hb1e8313_2
fastcache 1.1.0 py38h1de35cc_0
filelock 3.0.12 py_0
flake8 3.8.3 py_0
flask 1.1.2 py_0
freetype 2.10.2 ha233b18_0
fsspec 0.7.4 py_0
future 0.18.2 py38_1
get_terminal_size 1.0.0 h7520d66_0
gettext 0.19.8.1 hb0f4f8b_2
gevent 20.6.2 py38haf1e3a3_0
glib 2.65.0 hc5f4afa_0
glob2 0.7 py_0
gmp 6.1.2 hb37e062_1
gmpy2 2.0.8 py38h6ef4df4_3
greenlet 0.4.16 py38haf1e3a3_0
h5py 2.10.0 py38h3134771_0
hdf5 1.10.4 hfa1e0ec_0
heapdict 1.0.1 py_0
html5lib 1.1 py_0
icu 58.2 h0a44026_3
idna 2.10 py_0
imageio 2.9.0 py_0
imagesize 1.2.0 py_0
importlib-metadata 1.7.0 py38_0
importlib_metadata 1.7.0 0