For the phase-senstive measurement of unconventional superconductor, e.g. cuprate superconductor, not only the corner Junction/SQUID, but also the self-generated flux on the tri-junction plays important role. Here, we study a recently discovered family of superconductors A2Cr3As3 (A = K, Rb, Cs), which were proposed theoretically to be p-wave superconductors. We fabricate both superconducting quantum interference devices (SQUIDs) on exfoliated K2Cr3As3, and perform the phase-sensitive measurement. It reveals the dominant second-order harmonic component in the supercurrent of these SQUIDs, revealing two ground states locating at +phi,-phi, respectively. By fast counting measurement, we do obverse these two self-generated fluxes in the SQUID, pointing to fractional-interger phases +phi(clockwise) and -phi(anti-clockwise). This is in favor of the spin-triplet p-wave pairing in K2Cr3As3.