Odd-parity error rejection (OPER), in particular the method of actively odd parity pairing (AOPP), can drastically improve the asymptotic key rate of sending-or-not-sending twin-field (SNS-TF) quantum key distribution (QKD). However, in practice, the finite-key effects have to be considered for the security. Here, we propose a zigzag approach to verify the phase-flip error of the survived bits after OPER or AOPP. Based on this, we can take all the finite-key effects efficiently in calculating the non-asymptotic key rate. Numerical simulation shows that our approach here produces the highest key rate over all distances among all existing methods, improving the key rate by more than 100% to 3000% in comparison with different prior art methods with typical experimental setting. These verify the advantages of the AOPP method with finite data size. Also, with our zigzag approach here, the non-asymptotic key rate of SNS-TF QKD can by far break the absolute bound of repeater-less key rate with whatever detection efficiency. We can even reach a non-asymptotic key rate more than 40 times of the practical bound and 13 times of the absolute bound with 10 12 pulses. © 2020 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische GesellschaftNew J. Phys. 22 (2020) 053048 C Jiang et al [73][74][75]. More precisely, we show that is able to beat the repeater-less PLOB bound [75] established by Pirandola, Laurenza, Ottaviani, and Banchi, which is the fundamental benchmark used in the literature. Experiments [76][77][78][79][80][81] have been done to demonstrate those protocols. In particular, the efficient variant of TF QKD, named sending-or-not-sending (SNS) protocol has been proposed in reference [12]. The SNS protocol has its advantage of tolerating large misalignment errors [12,18] and unconditional security with finite key size [21]. The numerical results show that the secure distance can exceed 500 km even when the misalignment error is as large as 20% [21]. The SNS protocol has been experimentally demonstrated in proof-of-principle in reference [76], and realized in real optical fiber with the finite-key effects taken into consideration [77,80]. Based on the idea of SNS, long distance side-channel-free QKD was proposed recently [9], using coherent states only.However, there are still considerable spaces to further improve the performance of the SNS protocol. For example, the original SNS protocol [12,18,21] is limited to small probability of sending a signal coherent state and this limits its key rate.There are several methods proposed in reference [22] to improve the key rate of SNS protocol, such as the standard error rejection and odd-parity error rejection (OPER) including the method of actively odd parity pairing (AOPP) with infinite key size. Among all those methods, the numerical results show that the OPER, especially the AOPP methods can drastically improve the key rate and secure distance of SNS protocol with infinite key size. But to show the advantage of OPE...