The phonology of Old Kangshi is very similar to that of the Court Kangshi of YP. It distinguishes almost exactly the same consonants:

	Labial	Alveolar	Alveolar-Sibilant	Retroflex	Velar	Uvular
Nasal	m <m>	n <n>			ŋ <ñ>
Stop	p <p>	t <t>	ts <ts>		k <k>	q <q>
Voiced Stop	b <b>	d <d>	dz <dz>
Fricative			s <s>		x <x>
Voiced Fricative			z <z>	dʐ~ʐ~ʂ <r>	ɣ <g>	h <ʁ>

The cardinal vowels are also the same as in modern Court Kangshi, but there are more diphthongs. The original high-mid diphthongs also lower to high-low breaking diphthongs in Court Kangshi.

/æ a e ɤ o i ɯ u/ <c a e v o i w u>
/æi aɯ au ei ɤɯ ou ɤi ɯi ɤu ɯu ie ɯɤ uo/ <ci aw au ei vw ou vi vu wi wu ie wv uo>

The phonotactics are different as well. Old Kangshi still retains the three-way distinction between nonsyllabic preinitial consonants, (sesqui)syllabic ones followed by an ultrashort vowel [ə̆] <.> and full syllables where the vowel is <v>. Additionally, in addition to the modern Court Kangshi codas -b and -g, it still retains the coda -d, like in <gdzod>. This shows up in loanwords in ways pointing to a perhaps dialectal, perhaps free variation between [ð] and [d] or perhaps [t̚].

Finally, Old Kangshi has a larger tone inventory than Kangshi proper:
/high, high falling, rising, mid, low falling, low/ = <-h -x -t -0 -z -j>.