  The purpose of the present study is to explore the mass spectrum of the
hidden charm tetraquark states within a diquark model. Proposing that a
tetraquark state is composed of a diquark and an antidiquark, the masses of all
possible $[qc][\bar{q}\bar{c}]$, $[sc][\bar{s}\bar{c}]$, and
$[qc][\bar{s}\bar{c}]$ $\left([sc][\bar{q}\bar{c}]\right)$ hidden charm
tetraquark states are systematically calculated by use of an effective
Hamiltonian, which contains color, spin, and flavor dependent interactions.
Apart from the $X(3872)$, $Z(3900)$, $\chi_{c2}(3930)$, and $X(4350)$ which are
taken as input to fix the model parameters, the calculated results support that
the $\chi_{c0}(3860)$, $X(4020)$, $X(4050)$ are $[qc][\bar{q}\bar{c}]$ states
with $I^GJ^{PC}=0^+0^{++}$, $1^+1^{+-}$, and $1^-2^{++}$, respectively, the
$\chi_{c1}(4274)$ is an $[sc][\bar{s}\bar{c}]$ state with
$I^GJ^{PC}=0^+1^{++}$, the $X(3940)$ is a $[qc][\bar{q}\bar{c}]$ state with
$I^GJ^{PC}=1^-0^{++}$ or $1^-1^{++}$, the $Z_{cs}(3985)^-$ is an
$[sc][\bar{q}\bar{c}]$ state with $J^{P}=0^{+}$ or $1^+$, and the
$Z_{cs}(4000)^+$ and $Z_{cs}(4220)^+$ are $[qc][\bar{s}\bar{c}]$ states with
$J^{P}=1^{+}$. Predictions for other possible tetraquark states are also given.
