In order to discuss the potential impact of solar superflares on space weather, we investigated statistical relations among energetic proton peak flux with energy higher than $ 10 rm MeV$ ($F_p$), CME speed near the Sun ($V_{CME}$) obtained by {it SOHO}/LASCO coronagraph and flare soft X-ray peak flux in 1-8AA band ($F_{SXR}$) during 110 major solar proton events (SPEs) recorded from 1996 to 2014. The linear regression fit results in the scaling relations $V_{CME} propto F_{SXR}^alpha$, $F_ppropto F_{SXR}^beta$ and $F_ppropto V_{CME}^gamma$ with $alpha = 0.30pm 0.04$, $beta = 1.19 pm 0.08$ and $gamma = 4.35 pm 0.50$, respectively. On the basis of simple physical assumptions, on the other hand, we derive scaling relations expressing CME mass ($M_{CME}$), CME speed and energetic proton flux in terms of total flare energy ($E_{flare}$) as, $M_{CME}propto E_{flare}^{2/3}$, $V_{CME}propto E_{flare}^{1/6}$ and $F_{p}propto E_{flare}^{5/6}propto V_{CME}^5$, respectively. We then combine the derived scaling relations with observation, and estimated the upper limit of $V_{CME}$ and $F_p$ to be associated with possible solar superflares.