The flavour changing neutral current decays are interesting probes for new physics searches. The angular distributions of $b \to s \ell^+ \ell^-$ transition processes of both $\mathrm{B}^0 \to \mathrm{K}^{*0} \mu^ +\mu^-$ and $\mathrm{B}^{+} \to \mathrm{K}^{+} \mu^+\mu^-$ decays are studied using a sample of proton-proton collisions at $\sqrt{s} = 8~\mathrm{TeV}$ collected with the CMS detector at the LHC, corresponding to an integrated luminosity of $20.5~\mathrm{fb}^{-1}$. Angular analyses are performed to determine the angular parameters $P_1$ and $P_5'$ for $\mathrm{B}^0 \to \mathrm{K}^{*0} \mu^ +\mu^-$ and $A_{FB}$ and $F_{H}$ parameters for $\mathrm{B}^{+} \to \mathrm{K}^{+} \mu^+\mu^-$, as functions of the dimuon invariant mass squared. All the measurements are consistent with the standard model predictions. In addition, the projections for the sensitivity of the measurement of the $P_5'$ parameter in the $\mathrm{B}^0 \to \mathrm{K}^{*0} \mu^ +\mu^-$ angular analysis at the High-Luminosity LHC is reported.